Istituto di Fisica dello Spazio Interplanetario V. Iafolla, E. Fiorenza, C. Lefevre, S. Nozzoli, R....

Istituto di Fisica dello Spazio Interplanetario

V. Iafolla, E. Fiorenza, C. Lefevre, S. Nozzoli,

R. Peron, M. Persichini, A. Reale, F. Santoli

Istituto di Fisica dello Spazio Interplanetario (IFSI/INAF), Roma, Istituto di Fisica dello Spazio Interplanetario (IFSI/INAF), Roma, ItalyItaly

ISA on the Moon: an instrument proposal for the ILN (International

Lunar Network)

ISA on the Moon: an instrument proposal for the ILN (International

Lunar Network)

EGU General Assembly 2009Vienna, Austria, 19 – 24 April 2009


Renewed interest for the Moon

Nearest body outside EarthSolar System historyOutpost for Solar System settlementQuiet placeFundamental physics

Photo Apollo 11


Lunar Laser Ranging

Three retroreflectors arrays were carried on The Moon by Apollo missions and two by Soviet missions

Probably the most important scientific contribution from Apollo missions!

Selenodesy Lunar rotation General relativity


Constraints on formation, evolution and present state of the Moon come from:Surface compositionMagnetic fieldGravitational fieldSelenoseismology

Moon history

Picture NASAPicture ESA


ISA: the accelerometer

ISA sensing element

ISA pick-up



Geostar

Gradiometer

GReAT

BepiColombo


The mission MAGIA

MAGIAMAGIA (Missione Altimetrica Missione Altimetrica Gravimetrica Geochimica lunAreGravimetrica Geochimica lunAre) is a Moon exploration mission proposal (funded by Agenzia Spaziale Italiana)

Scientific Scientific objectivesobjectives

• Detailed study of the internal structureinternal structure of the Moon through its gravitygravity and figurefigure

• Study of the polar and subpolar regionspolar and subpolar regions in terms of their morphologymorphology and mineralogymineralogy

• Study of the lunar exosphere and radioactive lunar exosphere and radioactive environmentenvironment

• Improved measure of the gravitational redshiftgravitational redshift measurements from a circumlunar platform

• Determination of the position of the seleno-position of the seleno-centercenter

ISA contributio

n


ISA-S: the seismometer

The accelerometer, placed on ground, is directly sensitive to seismic disturbances, and therefore acts as a seismometer acts as a seismometer without any changeswithout any changes

The three sensing elements are arranged with their centers of mass along the same axis (the local vertical)

tiltmeters

gravimeter

local vertical


12.74 12.75 12.76 12.77 12.78 12.79 12.8

-8.246

-8.244

-8.242

-8.24

-8.238

-8.236

x 10-3

Ac

ce

lera

zio

ne

[g

]

Tempo giorni dal 2001

Misure GEOSTAR

Earthquakes 13 gen 2001 17:33:29:22Off Coast of Central AmericaRegistrazione Gravimetro Geostar Ustica

Solid tide of Earth Solid tide of Earth

Teleseismic (free oscillation of Earth)Teleseismic (free oscillation of Earth)

Seismic NoiseSeismic Noise

Seismic measurements


Parameter Value Remarks

Measurement Accuracy 10-9 m/s2 Accuracy required for the acceleration measurements

ISA-S intrinsic random noise

S0(f) = 10-9 m/s2/Hz1/2 Level of the total random noise in the ISA measurements process

Frequency Range 10-5 – 1 HzThe max resolution is obtained inside the frequency band, but ISA-S can works quite well also at frequency out of the indicated band, increasing the bit rate and taking into account the mechanical transfer function

Dynamic range 106 Set by the acquisition system and converter

Frequency readout interval 1 sThe required data rate is 1 sample/s for the three acceleration components and the three sensing temperatures

Resonance frequency 3.5 Hz Frequency of the mechanical oscillator

Quality factor Q 10 Quality factor of the oscillator

Thermal stability x,y 5∙10-7 m/s2/°C ISA-S thermal stability for the two tiltmetric components

Thermal stability z 1.6∙10-6 m/s2/°C ISA-S thermal stability for the gravimetric component

Mass, total 5.5 kg ISA-S Total mass

Dimension 300 x 300 x 300 mm

Electronic power dissipation

6 W ISA-S Total power dissipation

Data rate (nominal) 15 kbit/s

Capability of ISA-S /Capability to recover the local vertical autonomously, in order to operate with two of its elements like tiltmeters and one like gravimeter

ISA-S: the seismometer


Requirements

Science GoalScience GoalUnderstand the current seismic state of the Moon, and determine the internal structure of the Moon.2) Detection of new aggregate states of matter (e.g., strange quark nuggets)

Network RequirementNetwork RequirementMultiple, simultaneously operating sites about the Moon are required to interpret seismic events2) Multiple, simultaneously operating sites about the Moon are required to interpret seismic events.

Science RationaleScience RationaleSeismic waves from lunar tectonic events can be used to determine the structure and composition of the crust, mantle and core.2) The existence of strange quark nuggets is an important prediction which could also provide a candidate for Dark Matter.

Measurement RequirementsMeasurement RequirementsMeasure lunar seismicity using broad-band seismometry at multiple, geographically dispersed, locations.2) Measure lunar seismic events using broad-band seismometry at no fewer than 5 geographically dispersed locations.

Seismometry New fundamental physics

ILN Core Instrument Working group


Requirements

Mission RequirementsMission RequirementsAt least 4 sites simultaneously operating for 6 years. Inter-station timing accuracy: 5ms. Instrument attached to ground and vibrationally isolated from the spacecraft.2) Detection of strange quark nuggets via epilinear seismic source identification requires at least 5 sites simultaneously operating for as many years as possible.

Instrument RequirementsInstrument RequirementsThree axis Very Broad Band (VBB) seismometers with: Dynamic Range >24 bits; High Frequency Cutoff about 20 Hz. Sensitivity [0.001-0.1 Hz] 10-11m/s [0.1-1 Hz] 2x 10-11m/s [1-20Hz] 10-9m/s. Thermal stability +/_ 5deg with need to thermal blanket ground within 1m if surface deployed. Altitude knowledge.Same.

Mass, Power, ThermalMass, Power, ThermalMass 6 kg: Power 2 W(peak), and 1 W(cont.), and 0.2 W (low power). May need additional power for instrument heating.Same.

DataData100 Mbits per Earth day; no down link drivers.Same.

ILN Core Instrument Working group

Seismometry New fundamental physics


Site selection

Barbara Cohen (SDT Co-chair), The International Lunar Network (ILN) and the US Anchor Nodes mission, Update to the LEAG/ILWEG/SRR, 10/30/08Barbara Cohen (SDT Co-chair), The International Lunar Network (ILN) and the US Anchor Nodes mission, Update to the LEAG/ILWEG/SRR, 10/30/08

• Strong science desire for farside placement. Due to dependency upon communications satellite, SDT also identified suitable nearside sites.

• Node 1 must be placed antipodal to a moonquake epicenter known by the Apollo network: -5°S, 75°W is only nearside site

• Node 2 must be placed within ~30° of the same epicenter, so could also be nearside 2: 30°N, 75°E

• Nodes 3 and 4 should form a triangle with western node, preferably on the farside

• Site selection criteria will also involve desires from engineering for DV and comm


Thermal issues

http://www.asi.org/adb/02/05/01/surface-temp-chart.html

More than 200 °C range during lunar day

104 m/s2 for the most sensitive (gravimetric)

component

Need for an adequate thermal control system!


Passive Seismic ExperimentPassive Seismic Experiment on Apollo 16

T. A. Sullivan, Catalog of Apollo Experiment Operations, NASA Reference Publication 1317

ISA thermal control system performanceISA thermal control system performance

Thermal issues

Istituto di Fisica dello Spazio Interplanetario V. Iafolla, E. Fiorenza, C. Lefevre, S. Nozzoli, R....

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