A. Milillo and K. C. Hsieh (and the SHEA fans!). 2nd SERENA-HEWG meeting - Mykonos, June. 2009 Why...
Transcript of A. Milillo and K. C. Hsieh (and the SHEA fans!). 2nd SERENA-HEWG meeting - Mykonos, June. 2009 Why...
A Milillo and K C Hsieh
(and the SHEA fans)
2nd SERENA-HEWG meeting - Mykonos June 2009
Why energetic neutral atoms are a useful tool for planetary investigationsThe neutral atoms do not interact with electromagnetic fields Hence if their energies are high enough to consider the gravitational effects negligible they have the property to maintain their characteristics (energy distribution and direction) unchanged since the generation time In this way the information about the (remote) generation process can be obtained through energetic neutral atom detectionWe know two main generation mechanisms of atoms at energies well above the gravitational effects Charge-exchange and ion sputtering processes
Plasma
ionsions
keV ENA
ENA features in the solar system
Charge-ExchangeCharge-Exchange
SurfaceSurfaceIon-SputteringIon-Sputtering
10s eV ENA
ionsions
AtomosphericAtomosphericIon-SputteringIon-Sputtering
10s eV ENAionsions
(fm Orsini et al SERENA-HEWG meeting Santa Fe NM USA)2nd SERENA-HEWG meeting - Mykonos June 2009
OutlineSurface ion sputtering process Other surface release processes
(example of Mercury)Expected outcomes from Sputtered
High-Energy Atoms (SHEA) observations in the Hermean environmentin the solar wind - asteroid
interactionin the Jupiterrsquos system
Conclusions 2nd SERENA-HEWG meeting - Mykonos June 2009
Surface Ion Sputtering process
Ion sputtering products depend onbull the composition and the chemical structure of the surface bull the impinging plasma flux
Release of neutrals due to bombardment of a surface by energetic ions
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Why energetic neutral atoms are a useful tool for planetary investigationsThe neutral atoms do not interact with electromagnetic fields Hence if their energies are high enough to consider the gravitational effects negligible they have the property to maintain their characteristics (energy distribution and direction) unchanged since the generation time In this way the information about the (remote) generation process can be obtained through energetic neutral atom detectionWe know two main generation mechanisms of atoms at energies well above the gravitational effects Charge-exchange and ion sputtering processes
Plasma
ionsions
keV ENA
ENA features in the solar system
Charge-ExchangeCharge-Exchange
SurfaceSurfaceIon-SputteringIon-Sputtering
10s eV ENA
ionsions
AtomosphericAtomosphericIon-SputteringIon-Sputtering
10s eV ENAionsions
(fm Orsini et al SERENA-HEWG meeting Santa Fe NM USA)2nd SERENA-HEWG meeting - Mykonos June 2009
OutlineSurface ion sputtering process Other surface release processes
(example of Mercury)Expected outcomes from Sputtered
High-Energy Atoms (SHEA) observations in the Hermean environmentin the solar wind - asteroid
interactionin the Jupiterrsquos system
Conclusions 2nd SERENA-HEWG meeting - Mykonos June 2009
Surface Ion Sputtering process
Ion sputtering products depend onbull the composition and the chemical structure of the surface bull the impinging plasma flux
Release of neutrals due to bombardment of a surface by energetic ions
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Plasma
ionsions
keV ENA
ENA features in the solar system
Charge-ExchangeCharge-Exchange
SurfaceSurfaceIon-SputteringIon-Sputtering
10s eV ENA
ionsions
AtomosphericAtomosphericIon-SputteringIon-Sputtering
10s eV ENAionsions
(fm Orsini et al SERENA-HEWG meeting Santa Fe NM USA)2nd SERENA-HEWG meeting - Mykonos June 2009
OutlineSurface ion sputtering process Other surface release processes
(example of Mercury)Expected outcomes from Sputtered
High-Energy Atoms (SHEA) observations in the Hermean environmentin the solar wind - asteroid
interactionin the Jupiterrsquos system
Conclusions 2nd SERENA-HEWG meeting - Mykonos June 2009
Surface Ion Sputtering process
Ion sputtering products depend onbull the composition and the chemical structure of the surface bull the impinging plasma flux
Release of neutrals due to bombardment of a surface by energetic ions
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
OutlineSurface ion sputtering process Other surface release processes
(example of Mercury)Expected outcomes from Sputtered
High-Energy Atoms (SHEA) observations in the Hermean environmentin the solar wind - asteroid
interactionin the Jupiterrsquos system
Conclusions 2nd SERENA-HEWG meeting - Mykonos June 2009
Surface Ion Sputtering process
Ion sputtering products depend onbull the composition and the chemical structure of the surface bull the impinging plasma flux
Release of neutrals due to bombardment of a surface by energetic ions
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Surface Ion Sputtering process
Ion sputtering products depend onbull the composition and the chemical structure of the surface bull the impinging plasma flux
Release of neutrals due to bombardment of a surface by energetic ions
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion-sputtering processThe emitted neutral flux n is proportional to the yield Y (the number of sputtered atoms produced by one single impinging ion) much higher for higher energies and for heavier ions (Baragiola et al 2003)
max
min
E
E
iieSi
I
e
n dEEEfdE
dcY
dE
d
c is the surface relative abundance of the atomic species considered I is the ion flux and fs is the energy distribution function
2nd SERENA-HEWG meeting - Mykonos June 2009
Note that the yields obtained by laboratory simulations could be different (lower or higher) in the planetary environments since the aggregation status of the surface material could be different from the sampleNew observations are really
important in this frame
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Energy distribution function
Directional neutrals
Ei incident particle energyEb binding energy 1 eVEe Energy of the released particle
2
1
221
213 4
1
mm
mmE
EE
EE
EcEEf
i
be
be
enieS
0
1ees dEEf
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes
(Killen et al SSR2008)
Thermal Desorption (TD) mainly volatiles at very low energies (lt5 eV)
Photon Stimulated Desorption (PSD) mainly volatiles at low energy (~ 1 eV)
Micrometeoroid Impact Vaporization (MIV) all the surface components at high energy but anyway below few eVs
Ion Sputtering (IS) all the surface components at higher energy up to 100s eV
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Particle release processes at Mercury Na case TD PSD
IS MIV
(Milillo et al PSS in press2008)2nd SERENA-HEWG meeting - Mykonos June
2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Detection of exospheric gas Observation of the global exospheric distribution (released particles) with characterization of composition can be obtained by mass spectrometers as well as UV spectrometersNa K and Ca densities of the Hermean exosphere can be obtained by ground-based observationsThese exospheric observations cannot provide univoche information about the parent surface release process neither about the location of the releaseOnly speculations about asymmetries induced by solar wind-planetary magnetosphere interaction or preferential released species can be done to discriminate the ion sputtering process
Why is it important to discriminate the action of the ion sputteringThe ion-sputtering process is one of
the main processes responsible for refractories release and escape Its action could be much more important in the last phases of the Solar System formations (about 45 Gy ago) when the early Sun was emitting a 100-times more intense slar wind (Lammer et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEAThe Sputtered High Energy Atoms (SHEA) that is the
high energy tail of the sputtered distribution (letrsquos say at energy Eegt10 eV) are between few and tens of the total release depending mainly on the ion impacting energy
2nd SERENA-HEWG meeting - Mykonos June 2009
Directional neutrals
Why do we wish to detect SHEA (neutrals at energies gt10 eV) to investigate the ion sputtering processBecause below 10 eV the ion-sputtering
product is negligible compared to other release process and the particles do not maintain the initial direction since the gravitational effects are not negligible
Energy distribution of the sputtered H2O particles emerging from the surface of Europa in case of S+ at 10 keV and 100 keV Binding energy is assumed 045 eV
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
(Environment Simulation ToolIFSI)
Particles released at different energy rangesEnergy range lt006 eVEnergy range 006-03 eVEnergy range 03-15 eVEnergy range 15-10 eVEnergy range 10-40 eVEnergy range 40-200 eV
2nd SERENA-HEWG meeting - Mykonos June 2009
SHEA detection provides a map of plasma precipitation regions and an imaging of particle emission from surfaceWe do not need to perform line-of-
sight integration hence the geometry of deconvolution is easier The problem here is the number of
unknown parameters Y (surface mineralogy Eb ) c Fion (species energy impact angle)
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Expected outcomes of SHEA observations Mercury case
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
The Solar wind and IMF at MercuryThe Parker spiral forms an angle of
about 20deg with the solar wind radial direction less than half of the value at the Earthrsquos orbit (~45deg) this implies a change of the relative ratio of the Interplanetary Magnetic Field (IMF) components with respect to the near-Earth conditions and an increase of the weight of the IMF Bx component
The average solar wind density is about ten times higher than that at the Earth but this value varies considerably due to the high eccentricity of the orbit of the planet (from 32 cm-3 to 73 cm-3)
B
The IMF intensity changes by a similar factor
B v
v
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Mercury has an internal magnetic fieldThe Mariner 10
observations confirmed by the first MESSENGER flyby reveal the existence of an internal dipolar-like magnetic field (Ness et al 1975)
(Milillo et al 2005)
The estimated dipole moment ranges between 284 and 358 nT RM
3 nothward oriented
Hermean magnetosphere is only 5 of that of the Earth In a zero order analysis the spatial dimensions must be scaled by a factor of ~7 or 8
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Solar wind entry in the Hermean magnetosphere
Density of the solar wind protons in from 105 to 1085 m-
3 The yellow lines represent the magnetic field (Kallio et al 2008)
The IMF orientation and intensity and the weak internal magnetic field of Mercury likely produce a direct entry through the cusps inside the Hermean dayside magnetosphere
Solar wind plasma circulates inside the magnetosphere and eventually may hit the surface
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
SW precipitation
(Massetti et al 2003)
BIMF =(00-10) nT
BIMF =(05-10) nTPdyn=16 nPa
BIMF =(05-10) nTPdyn=60 nPa
Flux(cm
-2 s sr keV)
-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Color and albedo controlled by maturity and composition
PC 2 interpreted to represent compositional variation
Caloris Basin smooth plains
Lowalbedo material
Smooth plainsLow albedo
MNF (minimum noise fractionsimilar to PC) 2-1-3 as R-G-B
Lowalbedomaterialldquostreakrdquo
From Robinson et al LPSC 2008
2nd SERENA-HEWG meeting - Mykonos June 2009
Fm Sprague et al SERENA-HEWG meeting Santa Fe NM May 2008
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
As well as for the cameras a FOV perpendicular to the sc motion is the most suitable for this kind of surface imaging
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Simulation of SHEA detection at Mercury by
BepiColomboMPOSERENA-ELENA
(Orsini et al 2008)
2nd SERENA-HEWG meeting - Mykonos June 2009
Thanks to the BepiColombo mission we will have simultaneous measurements of precipitating plasma (MIPA) surface composition (MIXS) and mineralogy (MERTIS) and neutral composition (STROFIO and PHEBUS) and SHEA observation (ELENA) for a complete investigation of the IS process
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Near Earth Object (NEO)bull have orbits with perihelion distances q lt13bull appear heterogeneous in shapes sizes spin rates and compositionsbull are subjected to continuous interaction with the interplanetary medium
bull solar wind interaction with surface (ion sputtering)
bull solar and cosmic ray bombardment
bull micrometeoroids gardening
NEO (433) Eros (John Hopkins
University)
The NEO superficial composition is modified by this space weathering
2nd SERENA-HEWG meeting - Mykonos 8-11 June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering NEObullIon fluxes Solar wind at 1 AU 1-keV H+ flux 108 (cm-2 s-1 sr keV)
bullThe binding energy Eb holding the regolith (strongly dependent from NEO type) ranges between 05 and 3-4 eV (Lammer et al 2003) We consider 2 eV
bullThe average yield Y in this case is about 005 (Lammer et al 2003)
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
100100100Total
111Ni28
151713 Fe26
111 Ca20
536 S16
161914 Si14
221 Al13
182015 Mg12
12811 C6
302938H1
Tagish Lake(atoms)
CM(atoms)
CI (atoms)
ElementZ
Bulk element abundances for CI type chondrites
(Plainaki et al 2008 adapted from Brown et al 2000)
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtered fluxes of individual species
bull The most important contribution to the total sputtered particle flux comes from sputtered H bullMg is also significantly lost for ion-sputtering action (Plainaki et al 2008)
m-2 s
-1m
-2 s-1
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Total sputtered flux from a CI type NEOm
-2 s-1
Particles fluxes (up to 1011 particles m-2 s-1) appear in a region up to 1 km above the NEO surface (in the solar wind direction) The erosion rate fω
is 03 Aringyear where ω=10-29 m3 is the atomic volume in a solid substance (Plainaki et al 2008) This result is similar to
the estimation performed for the lunar surface 02 Aringyear in case of solar wind sputtering (Starukhina 2003)
2nd SERENA-HEWG meeting - Mykonos June 2009
The SHEA (gt10 eV) flux results in about 109 particles m-2 s-1
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
ENA in the Jupiter environment
SHEAfrom Europa
and GanymedeC-E ENA
from plasma ndash tori interaction
C-E ENA from auroral regions
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
2nd SERENA-HEWG meeting - Mykonos June 2009
(Paranicas et al GRL 2002)
Krupp et al 2001 showed that the radiation belts extends inside the Callistorsquos while the energetic particle fluxes decrease abruptly out of these distances Plasma precipitation on the inner moonsrsquo surfaces produces SHEA
Giovian radiation belt
Ganymedersquosorbit
Callistorsquosorbit
Europarsquosorbit
H+ O+ S+
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Europa
Surface composed mainly by water ice and other components as Na K etc In fact Na and K atmosphere has been observed (Brown and Hill 1996 Brown 2001)Traces of non-icy material (a hydrate compound of H2O2 (013) SO2 and CO2) (Tiscareno and Geissler 2003 Johnson et al 1983)
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
The surface composition of Europa
Highest albedo among all the Galilean satellites (Kuskov and Kronrod 2005)
Probably geologically young surface (crater preservation yields an age estimate of ~10ndash100 Ma) (Moore et al 1998)
Possible existence of liquid water beneath the outer icy crust that ranges from a few kilometers to at least a few tens of kilometers (McKinnon 1999 Ruiz and Tejero 2003)
Disrupted ice crust in the Conamara region of Jupiters moon Europa (NASA courtesy)
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Ion sputtering EuropabullIon fluxes based on values given by Cooper et al (2001) and Strazzulla et al (2003) at energy about 10-100 keV
Particle Flux (ions cm-2 s-1)
H+ 15 ∙107
C+ 18 ∙106
O+ 15 ∙106
S+ 9∙106
bullThe binding energy Eb holding the ice molecules on the surface of Europa is characterized by the sublimation energy of water 045 eV per molecule (Johnson 1998) Particle Sputtering Yield
(moleculesion)
H+ 5
C+ 10
O+ 50
S+ 30
bullThe yield Y are based on the results by Shi et al (1995) Johnson (1990) and Ip et al (1997) as well as on the Galileo observations
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Sputtering Europa
SHEA flux produced by S+ impinging particles
(Plainaki et al Cospar meeting 2008)
particlessm2
The estimated SHEA (gt10 eV) signal at 200 km over Europarsquos surface is f=107 (cm2 s)-1
Flux (particles m
-2 s-1)
H+ O+C+ S+
(Plainaki et al EGU 2009)
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Similar energetic ion fluxes observed by Galileo spacecraft at Europa (Paranicas et al GRL 2002) are expected at Ganymede that is composed by a similar iced surface but it has the peculiarity of an internal magnetic field that could shield the plasma or define preferential entries and plasma precipitation regions
Comparative observations
2nd SERENA-HEWG meeting - Mykonos June 2009
From the NASAESA JOINT SUMMARY REPORT EUROPA JUPITER SYSTEM MISSION
On the contrary the ion fluxes at Callisto are two order of magnitude lower
Similar observations in different environment like the two moons Europa and Ganymede would offer the chance to investigate the different satellites evolution in the Jupiter system
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Conclusions Why is ion-sputtering investigation important
Interaction plasma-surface or plasma-atmosphere
Characterization of the surface propertiesInvestigation of the particles escape mechanismsPlasma entry and circulation in planetary
environmentsCharacterization of the effect of space
weathering on the surfacesEventually investigation of the evolution of Solar
system2nd SERENA-HEWG meeting - Mykonos June
2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Conclusions Why is SHEA imaging important as well as of surrounding gas analysis The detection of particles above 10 eVs is a method to identify that the ion-sputtering is active and to define the region of its action A joint observation of surronding gas and SHEA will permit to know where when and how the ion sputtering release takes place and will permit a clearer estimation of the escaping material
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
ENVIRONMENTS I
NVESTIGATED V
IA S
HEA
2nd SERENA-HEWG meeting - Mykonos June 2009
ENCELADUS
NEO
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009
Thank you for your
attention
2nd SERENA-HEWG meeting - Mykonos June 2009