1. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK In-situ Science on the surfaces of Ganymede and Europa 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

2. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK Contents  Introduction  Current status  Europa & Ganymede compare and contrast  Europa  Ganymede  Summary

3. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK Descent Module release from Orbiter Reorient Spin-up & Decelerate Penetrator Separation Penetrator & PDS surface Impact Spin-Down Penetrators Delivery sequence courtesy SSTL Operate from below 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

4. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK Penetrator 20-60 cm 5-15 kg Payload ~2 kg

5. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK Radiation sensor Magnetometers Batteries Mass spectrometer Micro-seismometers Drill assembly Accelerometers Power Interconnection Processing Accelerometers, Thermometer Batteries,Data logger Test Penetrator – internal architecture

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

7. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK GanymedeEuropa Both :- Icy bodies Varied terrains Some common surface features But distinct differences

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

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

10. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK In-situ Science Instruments radio beacon, seismometer, magnetometer, microphone, tiltmeter, descent cameraGeophysics – radio beacon, seismometer, magnetometer, microphone, tiltmeter, descent camera thermometer, conductivity, permittivity, microscope, accelerometerLocal geophysics – thermometer, conductivity, permittivity, microscope, accelerometer mass spectrometer, gamma-ray densitometer, neutron spectrometer, etc...Chemistry – mass spectrometer, gamma-ray densitometer, neutron spectrometer, etc...   Astrobiology – mass spectrometer, microscope, micro- thermogravimeter, redox, pH.   Ground truth – all   Support to future missions – accelerometer, seismometer, radiation monitor, thermometer, mass spectrometer.

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

12. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK 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 a) gray dilational bands [Schenk, 2009] – small slopes (average 5±2 ,15%>10  ) ~20km wide. – other regions analysed slopes<30  – age ? (effect of radiation) b) chaos, lenticulae regions [Proctor et al., Moscow, Feb09]. –reasonably flat/smooth in some areas –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 ?

13. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK 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 either an 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]

14. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK 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 right 25km Giese [1998], Oberst [1999] infer slopes in region 0-20  Uruk Sulcus and 0-30  for Galileo Regio.

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

16. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK - End - rag@mssl.ucl.ac.uk http://www.mssl.ucl.ac.uk/planetary/missions /Micro_Penetrators.php

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

18. EPSC Europlanet – Potsdam, Germany. Sep 16 2009 MSSL/UCL UK 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 to Soft Landers for in-situ studies