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In-situ Science on the surfaces of Ganymede and Europa with Penetrators

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.

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In-situ Science on the surfaces of Ganymede and Europa with Penetrators

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  1. 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: LancasterUniversity, UK. 9: Cavendish Laboratory, Cambridge, UK. 11: University ofAberystwyth, 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. Contents • Introduction • Current status • Europa & Ganymede compare and contrast • Europa • Ganymede • Summary

  3. Penetrators Spin-Down Descent Module release from Orbiter Spin-up & Decelerate Reorient Penetrator Separation Penetrator & PDS surface Impact • 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 Operate from below surface Delivery sequence courtesy SSTL

  4. Penetrator 5-15 kg Payload ~2 kg 20-60 cm

  5. Test Penetrator – internalarchitecture Mass spectrometer Radiation sensor Batteries Magnetometers Accelerometers Power Interconnection Processing Micro-seismometers Accelerometers, Thermometer Batteries,Data logger Drill assembly

  6. 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. Europa Ganymede • Both :- • Icy bodies • Varied terrains • Some common surface features • But distinct differences

  8. Europa Ganymede • 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 Galileo images

  9. 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. In-situ Science Instruments • Geophysics – radio beacon, seismometer, magnetometer, microphone, tiltmeter, descent camera • Local geophysics– thermometer, conductivity, permittivity, microscope, accelerometer • 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. Geophysics & Astrobiology… 3. Penetrator impact into upwelled zone of potential astrobiological material 2. communication of life forms to surface 1. habital zone on ocean floor adjacent to nutrients Adapted from K.Hand et. al. Moscow’09, who adapted it from Figueredo et al. 2003

  12. E.g. Castalia Macula Europa - Impact Sites [Schenk, 2009] • Pointy penetrator– better for chemistry, seismometry.– slopes <~30 (to avoid ricochet) • Spherical penetrator – any area, but reduced science capability. • 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]. • reasonably flat/smooth in some areas • young. What are slopes for much smaller scale lengths ?Can we use knowledge of likely regolith mechanical structures ? [Proctor et al., Moscow, Feb09].

  13. 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]

  14. Ganymede continued.. • Bright material on peaks & dark materialin 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) Giese [1998], Oberst [1999] infer slopes in region 0-20 Uruk Sulcus and 0-30 for Galileo Regio. Portion of Galileo Regio (old dark terrain) Note smoother area on right 25km

  15. 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. - End - rag@mssl.ucl.ac.uk http://www.mssl.ucl.ac.uk/planetary/missions/Micro_Penetrators.php

  17. 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. 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

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