epsc europlanet – potsdam, germany. sep 16 2009 mssl/ucl uk in-situ science on the surfaces of...

EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK

In-situ Science on the In-situ Science on the surfaces of Ganymede and surfaces of Ganymede and

Europa with PenetratorsEuropa with Penetrators

Rob Gowen (MSSL/UCL, UK)Adrian Jones (UCL)

on behalf of Penetrator Consortium

1: Mullard Space Science Laboratory, University College London, 2: Planetary and Space Sciences Research Institute, Open University, UK. 3:Birkbeck College, University of London, UK. 4: Surrey Space Centre, Guildford, UK. 5: Imperial College, London,

UK, 6: University of Leicester, UK. 7: University College London, UK. 8: Lancaster University, UK. 9: Cavendish Laboratory, Cambridge, UK. 11: University of Aberystwyth, UK. 12: Istituto di Fisica dello Spazio Interplanetario-INAF, Roma, Italy. 13: DLR,

Berlin, Germany. 14: Institute of Microelectronics and Microsystem-CNR, Roma, Italy. 15: Université Paris, France. 16: Centro de Astrobiologia-INTA-CSIC, España. 17: Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. 18:

DLR, Bremen, Germany. 19: Joint Institute for VLBI in Europe (JIVE), Dwingeloo, The Netherlands. 20: IWF, Space Research Institute, Graz, Austria. 21: Royal Observatory, Belgium


ContentsContents

IntroductionIntroduction Current statusCurrent status Europa & Ganymede compare and contrastEuropa & Ganymede compare and contrast EuropaEuropa GanymedeGanymede SummarySummary


Descent Module release from Orbiter

Reorient

Spin-up & Decelerate

Penetrator Separation

Penetrator & PDS Penetrator & PDS surface Impactsurface Impact

Spin-Down

PenetratorsPenetrators

Delivery sequence courtesy SSTL

Operate from Operate from below surfacebelow surface

Low mass projectiles

High impact speed ~ up to 400 ms-1

Very tough ~10-50kgee

Penetrate surface and imbed therein

Undertake science-based measurements

Transmit results


Penetrator

20-60 cm

5-15 kg

Payload ~2 kg


Radiation sensor

MagnetometersBatteries

Mass spectrometer

Micro-seismometers

Drill assembly

AccelerometersPowerInterconnectionProcessing

Accelerometers, ThermometerBatteries,Data logger

Test Penetrator – internal architecture


Current status

Penetrators proposed for EJSM (JGO & JEO)Ganymede & Europa (launch ~2020)

Funding to develop candidate instruments in UK and Europe

ESA ITT for study of descent module and penetrator platform elements study expected to commence Oct/Nov

Today - focus on science … as applied to penetrators


GanymedeEuropa

Both :-• Icy bodies• Varied terrains• Some common surface features• But distinct differences


GanymedeEuropa

Galileo images

• Much rugged terrain• Not all !• Ridges, cracks, bands, chaos • Few craters• Different surface material

• Much rugged terrain• Not all ! • Ridges, cracks, bands, chaos• Many craters• Different surface material


In-situ Science Capability

Geophysics – seismic activity, subsurface ocean, internal structure

Local geophysics – crustal strength, layering, mineralogy, temperature, conductivity, dielectric properties

Chemistry – chemical inventory (sample, volumetric)

Astrobiology – organic/inorganic chemical balance, UV flourescence, specific molecules, radioistopes

Ground truth – will also help interpretation of orbital data from other bodies

Support to future missions – landing sites characteristics (hardness), surface environment (radiation, temperature, magnetic field, quakes)


In-situ Science Instruments

• Geophysics – radio beacon, seismometer, magnetometer, radio beacon, seismometer, magnetometer, microphone, tiltmeter, descent cameramicrophone, tiltmeter, descent camera

• Local geophysics – thermometer, conductivity, permittivity, thermometer, conductivity, permittivity, microscope, accelerometermicroscope, accelerometer

• Chemistry – mass spectrometer, gamma-ray densitometer, neutron mass spectrometer, gamma-ray densitometer, neutron spectrometer, etc...spectrometer, etc...

Astrobiology – mass spectrometer, microscope, micro-thermogravimeter, redox, pH.

Ground truth – all

Support to future missions – accelerometer, seismometer, radiation monitor, thermometer, mass spectrometer.


Geophysics & Astrobiology…

Adapted from K.Hand et. al. Moscow’09, who adapted it from Figueredo et al. 2003

1. habital zone on ocean floor adjacent to nutrients

2. communication of life forms to surface

3. Penetrator impact into upwelled zone of potential astrobiological material


Europa - Impact Sites Pointy penetrator

– better for chemistry, seismometry.– slopes <~30 (to avoid ricochet)

Spherical penetrator – any area, but reduced science

capability.

E.g. Castalia Macula

Candidate sites of potential upwelled biogenic material

• gray dilational bands [Schenk, 2009]– small slopes (average 5±2,15%>10) ~20km wide. – other regions analysed slopes<30– age ? (effect of radiation)

• chaos, lenticulae regions [Proctor et al., Moscow, Feb09].

a) reasonably flat/smooth in some areas b) young.

[Schenk, 2009]

[Proctor et al., Moscow, Feb09].

What are slopes for much smaller scale lengths ?Can we use knowledge of likely regolith mechanical structures ?


Ganymede Largest of Jupiter’s Moons. Almost as big as Mars.

Only satellite known to have a magnetosphere (although swamped by Jupiter) – so magnetometer emplaced beneath the surface could be effective ?

Magnetosphere attributed to eitheran iron-rich core or to a salty sub-crustal ocean.- An ocean could harbour life, together with tidal energy source and connection to silicate nutrients (?)

Detection and characterisation desired (e.g. seismometer, radio beacon, magnetometer)

(orbital ground penetrating radar less effective with thick crust)

[Wikipedia]


Ganymede continued.. Bright material on peaks & dark material

in troughs – support theory of deposition [Oberst et al.,1999]- So dark material could be soft, thick and indicate areas of stable low slopes ? (could be good for impact)

Bright material believed to be ice, and dark material consistent with hydrated silicate minerals.- No current definitive knowledge of chemistry of this dark material (just consistent with spectra of such minerals) (direct chemical measurement required (e.g.mass spectrometer)

Portion of Galileo Regio (old dark terrain)

Note smoother area on right25km

Giese [1998], Oberst [1999] infer slopes in region 0-20 Uruk Sulcus and 0-30 for Galileo Regio.


Summary

Many benefits of in-situ science on Europa and Ganymede.– As individual objects– Supporting each others measurements– Supporting orbital data (ground truth) for Ganymede, Europa– Supporting orbital data of other bodies such as Callisto and Io.– Support for future soft lander missions.

Identified potential impact sites of low slopes, sizes and impact hardness characteristics

Further investigations in-progress


- End -- End -

[email protected]

http://www.mssl.ucl.ac.uk/planetary/missions/Micro_Penetrators.php


Scenarios

Pointy penetrator – better for chemistry, seismometry.– slopes <~30 (to avoid ricochet)

Spherical penetrator – impact any area – but reduced science capability for same mass.

2 or more penetrators– improved seismic ability– investigate more terrain types– natural redundancy


Why penetrators ?

Advantages: Low mass Simpler architecture Low cost Explore multiple sites Natural redundancy Direct contact with sub-regolith

(drill, sampling) Protected from environment

(wind, radiation)

Limitations: Low mass limits payload options Impact survival limits payload

options Limited lifetime Limited telemetry capacity

Complementary Complementary to Soft Landers to Soft Landers

for for in-situ in-situ studiesstudies

epsc europlanet – potsdam, germany. sep 16 2009 mssl/ucl uk in-situ science on the surfaces of...

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