Penetrators for Enceladus Dr Rob Gowen on behalf

Penetrators for Enceladus Dr Rob Gowen on behalf of UK Penetrator Consortium Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

What are Penetrators ? Detachable Propulsion Stage – Low mass projectiles ~5 Kg+PDS for Enceladus – High impact speed ~ 200 -500 m/s – Very tough ~10 -50 kgee Point of Separation Payload Instruments – Penetrate surface ~ few metres – Perform science from below surface Penetrator Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 PDS (Penetrator Delivery System) MSSL/UCL UK

Penetrator Payload/Science A nominal 2 kg payload … § Accelerometers – Probe surface/sub-surface material (hardness/composition) § Seismometers - Probe interior structure (existence/size of water reservoirs) and seismic activity of bodies § Chemical sensors – Probe surface refactory/volatile (organic/ astrobiologic) chemicals, perhaps arising from interior. § Thermal sensors - Determine subsurface temperatures and possibly probe deep interior processes. § Mineralogy/astrobiology camera – Probe surface mineralogy and possible astrobiological material. § + other instruments – to probe surface magnetic field, radiation, beeping transmitter, etc… § descent camera (surface morphology, landing site location, etc) Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Science/Technology Requirements § Target – E. g. region of upwelled interior material. – 2 penetrators would allow additional target, improved seismic results and natural redundancy but require 2 xmass. § Lifetime – Only minutes/hours required for camera, accelerometer, chemistry, thermal & mineralogy/astrobiologic measurements. – An orbital period (~few days) for seismic measurements. (requires RHU) § Spacecraft support – ~7 -9 years cruise phase, health reporting § Delivery – Targetting precision. – Ejection, descent motors & orientation, pre-impact separation, communications, impact. § Operation – Power/thermal (battery/RHU), data handling, communications. Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Preliminary Estimated Mass Item Estimated Mass (kg) Penetrator (inc. 2 kg payload) ~4. 5 Kg Delivery system(*) ~32 Kg Spacecraft support ~2. 5 kg Total mass ~39 Kg (*) heavy penalty for Enceladus delivery: estimate ~8 x(penetrator mass) with deployment from Titan with ∆V~3. 7 Km/sec Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Heritage § Lunar-A and DS 2 space qualified. § Military have been successfully firing instrumented projectiles for many years to comparable levels of gee forces into concrete and steel. § 40, 000 gee qualified electronics exist (and re-used). § Currently developing similar penetrators for Moon. LITE. § Payload heritage: – Accelerometers, thermometers, sample drill – fully space qualified. – Seismometers (Exo. Mars) & chemical sensors (Rosetta) heritage but require impact ruggedizing. – Mineralogy camera – new but simple. When asked to describe the condition of a probe that had impacted 2 m of concrete at 300 m/s a UK expert described the device as ‘a bit scratched’! Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Current Development Status Full-scale structure impact trial – Scheduled May 19 -23 2008 Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Current Development Status § Moon. LITE bids in preparation for : a) b) 5 inner compartments for full scale penetrator trial 2 yr development to bring ruggedization of penetrator subsystems and instruments up to TRL 5. Phase-A study for Moon. LITE mission, currently in discussion with BNSC and NASA. § Bids prepared for Cosmic Visions mission support. a) To study deltas to Moon. LITE (impact into ice, reduced mass penetrator, long descent, communications) • 3 penetrator firings • Normal incidence into dry sand at 300 m/s Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Main Technical Challenges § Ruggedisation to survive impact into ice (M→C) § Likely require RHUs for extended lifetime (requires good thermal model) (M→C) § Achieve proposed mass savings over Moon. LITE penetrators (reduced lifetime -> power saving, lighter structure, asics) (M→C) § Optimise mass estimates of descent system (M→C) § Study descent system in detail including target ellipse (C) § Study descent and landed communications including possible trailing aerial. (M→C) (M = Moon. Lite, C = Cosmic Vision, M→C ∆ development for Cosmic Vision) Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Penetrators for Titan ? § § § Could be delivered from balloon or orbit. Much smaller mass ~8. 5 Kg/probe Delivery from orbit allows : (i) deterministic targetting, and (ii) co-temporal placement of multiple penetrators for seismic network to allow investigation of subsurface oceans, interior/core, and seismic activity levels. § Multiple penetrators allows examining several different terrains (dunes, ice, lake beds) § Penetrators allow sampling from sub-surface e. g. bottom of lake beds which collect alluvial material deposits and possible astrobiologic material) Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

Further information and contact details email: rag@mssl. ucl. uk or see penetrator web site at http: //www. mssl. ucl. ac. uk/planetary/missions/Micro_Penetrators. php Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK

- End - Titan Saturn System Mission Workshop - Paris, Mar 17 -19, 2008 MSSL/UCL UK