The ALTEA and ALTEA-Shield experiments onboard the International Space Station
description
Transcript of The ALTEA and ALTEA-Shield experiments onboard the International Space Station
The ALTEA and ALTEA-Shield experiments onboard the
International Space Station
L. Di Fino, M. Larosa, L. Narici, V. ZaconteUniversity of Rome Tor Vergata
ALTEA (Anomalous Long Term Effects on Astronauts) – PI: Prof. L. Narici
Exposure of crew to space radiation poses one of the most significant hazards to space permanence.
A quest for understanding the risks for the Central Nervous System (CNS) during long permanence in space due to cosmic rays exposure.
Rationale:• anomalous Light Flash perceptions suggest that abnormal
(though possibly transient) CNS functional states may result• Theoretically predicted by Tobias: Tobias C.A. 1952 J. Aviat. Med. 23 345• First observed in 1969 by Aldrin during Apollo-11 mission
Scientific strategy:• detailed measurement of radiation environment (DOSI)• measurement of transient/long-term functional effects of space
environment and cosmic radiation on the CNS (CNSM)• survey of the radiation environment in space habitats (Survey)• test of shielding materials as countermeasures for CNS functional
risks (Shield)
Scientific goals
• Particle Detector (Silicon Detector System)6 Silicon Detector Units (SDU)
6 silicon planes – 8x16 cm2, 380 mm thickGeometrical factor
SDU 230 cm2srSDS 1180 cm2sr
Detectable LET range: 3 - 800 KeV/mm
ALTEA-Space facility
• EEG, VSU, Pushbutton• DAU
DOSI – CNSM configurations
Survey configuration
ALTEA facility onboard ISS
Onboard ISS since July 20062006-2007 ASI experiment2009-2010 NASA-SRAG experiment2010-2011 ESA experiment
> 800 days of acquisition time> 1 billion triggers
ALTEA facility onboard ISS
2006 2007 2008 2009 2010 2011 2012
DOSI (Dosimetry)Realtime measurement of radiation flux
Total acquisition time2006-2007: 224 days2009-2010: 320 days
CNSM (Central Nervous System Monitoring)
During a 90-minute session the astronaut wears EEG cap, slides under the SDS and signals LF perceptions
2006-2007: 7 sessions
ALTEA configurations
ALTEA-Shield SurveySame as DOSIDifferent 3D holderMeasurements in 4 different positions
Total acquisition time2006-2007: 281 days
Realtime data
ALTEA data are downloaded and analyzed in realtime at the ALTEA User Home Base (UHB) at University of Rome Tor Vergata.
A subset of ALTEA realtime data is publicly available through the NASA iNTEGRATED SPACE WEATHER ANALYSIS SYSTEM (iSWA) web application.http://iswa.ccmc.gsfc.nasa.gov
• 6 SDUs, triggered particles• pole/equator and orbit precession modulations • increment during passages on the SAA
Particle Rate
• Filter fast particles (ΔE ~ Z2)• Fit with a sum of Landau functions
Particle flux and ion abundances
December 2006 Solar Particle Event
Integrated Particle Fluxes and LET rates
MEAN POLES EQUATOR SAA0.00E+00
2.00E-03
4.00E-03
6.00E-03
8.00E-03
1.00E-02
1.20E-02
1.40E-02
Particle Flux (LET > 3 KeV/mm)
XYZ
Parti
cle
Flux
(par
t s-1
cm
-2 sr
-1)
MEAN POLES EQUATOR SAA0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
Particle Flux (LET > 50 KeV/mm)
XYZ
Parti
cle
Flux
(par
t s-1
cm
-2 sr
-1)
MEAN POLES EQUATOR SAA0.00E+00
5.00E-03
1.00E-02
1.50E-02
2.00E-02
2.50E-02
3.00E-02
3.50E-02
4.00E-02
LET rate (LET > 3 KeV/mm)
XYZ
LET
rate
(keV
mm
-1 s-
1 cm
-2 sr
-1)
MEAN POLES EQUATOR SAA0.00E+00
1.00E-03
2.00E-03
3.00E-03
4.00E-03
5.00E-03
6.00E-03
7.00E-03
8.00E-03
LET rate (LET > 50 KeV/mm)
XYZ
LET
rate
(keV
mm
-1 s-
1 cm
-2 sr
-1)
Parti
cle
Flux
LET
rate
Particle flux anisotropy
UsLab survey ALTEA-Shield integral fluxes (Preliminary)• Different positions and directions shows
similar fluxes except for Position1-Y• For LET>50KeV/mm direction X shows a flux
attenuation as expected
any LET LET > 50 keV/um
ConclusionsThe ALTEA-Space facility onboard ISS is used since 2006 in different experiments supported by all major space agencies.• It delivered a detailed measurement of the radiation environment
inside the UsLab, several measurements on astronauts and a survey of the radiation environment in different positions.
• A strong anisotropy (up to a factor 3 in LET) was found when considering high LET particles (LET > 50) coming from different directions.
• The second step of ALTEA-Shield (Shield) experiment is planned in 2012 to test the effectiveness of different shielding materials and thicknesses
• A collaboration with Jaxa is under consideration for further measurements on astronauts
At last… we are looking for students!
Thank you for your attention!
Particle flux anisotropy in raw angular flux distribution is masked by the SDUs’ angular acceptance.
A Montecarlo simulation (PHITS) of an isotropic flux was used to obtain each SDU angular acceptance.
METHOD: use ALTEA as single detector
To use ALTEA as a single detector we sum all the SDUs to obtain the angular acceptance of the whole ALTEA detector - R(q,j).
Parti
cle
Flux
LET
rate
Results: Poles SpectraZone B LPoles Any > 2Equator > 2.5*10-5 T < 2SAA < 2.5*10-5 T < 2
Parti
cle
Flux
LET
rate
Results: Equator SpectraZone B LPoles Any > 2Equator > 2.5*10-5 T < 2SAA < 2.5*10-5 T < 2
Parti
cle
Flux
LET
rate
Results: SAA SpectraZone B LPoles Any > 2Equator > 2.5*10-5 T < 2SAA < 2.5*10-5 T < 2
ALTEA - CNSM
7 sessioni eseguite, 3 Astronauti (1 sess + 2 sess + 4 sess)Astronaut LF Duration (min) Mean interval
(min)1 12 58 52 4 65 163 1 18 --2 0 63 --3 1 61 --2 1 62 --2 1 87 --
TOTAL 20 414 21
All E≤100 MeV/n E>100 MeV/nAll 18 2 16Z<6 16 2 14Z≥6 1.5 0.07 1.4
Numero di LF segnalati nelle sessioni CNSM
Rate di particelle passanti per l’occhio (part/min)
ALTEA - CNSM
Particella candidata (Z~3) alla generazione di un LF