ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Technical Trade Studies for a Lunar Penetrator Mission Alan Smith 1, Rob Gowen 1, Yang Gao 2, and Phil Church

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Contents  Introduction to Penetrators  MoonLITE Mission  Technical Trade Studies  Program Status  Summary & Conclusions

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 What are kinetic penetrators ? –Low mass projectiles ~2-13Kg –High impact speed ~ m/s –Very tough ~10-50kgee –Penetrate surface ~ few metres –Perform science from below surface Penetrator Point of Separation Payload Instruments Detachable Propulsion Stage PDS (Penetrator Delivery System)

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 History ? –No successful mission yet. –DS2 failed alongside soft lander. –Mars’96 spacecraft failed to leave Earth orbit. –Lunar-A cancelled but maybe fly on Lunar-Glob. Feasibility ? –Lunar-A and DS2 space qualified. –Military have been successfully firing instrumented projectiles for many years to comparable levels of gee forces into sand, concrete and steel. –40,000gee qualified electronics exist (and re-used) When asked to describe the condition of a probe that had impacted 2m of concrete at 300 m/s a UK expert described the device as ‘a bit scratched’!

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Impact Test

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007MoonLITE  Delivery and Comms Spacecraft (Orbiter). Deliver penetrators to ejection orbit. provide pre-ejection health status, and relay communications.  Orbiter Payload: 4 Descent Probes (each containing kg penetrator kg de-orbit and attitude control).  Landing sites: Globally spaced Far side, Polar region(s), One near an Apollo landing site for calibration.  Duration: >1 year for seismic network. Other science does not require so long (perhaps a few Lunar cycles for heat flow and volatiles much less).  Penetrator Design: Single Body for simplicity and risk avoidance. Battery powered with comprehensive power saving techniques Far side Polar comms orbiter

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 MoonLITE Payload & Key Objectives Accelerometer - Regolith mechanical strength - Depth of penetration Seismometers (& tiltmeter) - 3D structure of Lunar interior and core. - Characterize enigmatic strong surface quakes => Identify potentially dangerous sites for lunar bases Thermal - Presence of conducting volatiles - Heat flow -> Internal composition of moon. Geochemistry - Polar water and volatiles => Water is vital to manned missions - Astrobologically related material + Options : mineralogy camera, radiation monitor, magnetometer Minerals at poles and farside. Internal radiative composition. Remanent magnetism Total Mass ~2Kg

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007MoonLITE

Consider some Technical Challenges  Descent - deceleration, ACS  Structure – material, design  Comms – regolith, aerial  Lifetime – power, thermal (Others include data handling, impact physics, instruments..)

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Descent Systems Trade Study PDS Payload Delivery System Baseline ~ 13Kg penetrator Spacecraft ejection system ACS –Mechanism ? –Spinning ? Penetrator separation system Desire:- Landing ellipse not too large Impact angle <~45  to vertical Attack angle <8  Impact speed ~300ms Constraints: mass impact site contamination De-orbit Motor –Ensure orientation –Attack angle control (mass) –Penetrator mass –Fuel type (mass) –Impact angle –PDS land away from penetrator –Orientation disturbance of penetrator –Landing ellipse size Does not have to survive impact

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Penetrator Structure Trade Study Penetrator Baseline ~13kg ~120mm diameter ~60cm long Require:- Survive impact Ensure penetration depth ~2-5m Restrict deflection during impact Minimise forces on internal systems Constraints: mass impact site contamination MaterialMaterial Subsystems /payload mass Penetrator total mass Steel 6.5 Kg 27.4 Kg Aluminium 7.4 Kg 13.0 Kg Titanium 8.5 Kg 10.8 Kg Carbon Fibre * 7.3 Kg 10.5 Kg - Payload => size => mass - Diam/length ratio (impact deflection) - Penetration depth (shape) - Strength (apertures) - Integratibility/harnessing -=> thermal Design * is the only material which could allow heat flow without external thermal insulation

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Communications Trade Study Communications Baseline: Beagle2 Melacom, 6W.hr. One 90sec contact/15days Avg tel: 30kbits/day Avg cmd: low. Require:- Survive impact Communicate to orbit from beneath regolith Receive commands from orbit Possibly help with azimuthal orientation Constraints: mass power technology - Power vs Regolith attenuation (ice/volatiles, penetration depth ?) - Communication strategies => power - Commanding => seismometer event coordination Issues - Receiver/transmitter - Patch aerial (polarisation) - Trailing antennae ? (& aid heat flow measurement)

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Power-Thermal Trade Study Power Baseline ~500Wh, 2kg batteries solar cells – not at poles fuel cells – not studied RPG – when available Subsystems & instruments Heat losses –2 very different external environments:- equator ~250K very cold poles ~50-100K unknown conductivity (ice at poles?) –Thermal design keep batteries warm external/internal insulation parasitic heat losses through wires –Payload complement –Low power components –Low power operating modes seismometer monitoring mode limited comms periods –Fallback -> reduce seismometer lifetime at poles RHUs Keep batteries warm Desire: mission lifetime  1year for seismometry Constraints: mass/size rugged

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 MoonLITE Mission Status 1.Penetrator Design – baseline agreed. 2.Full-scale structure impact trial – Scheduled March Pre-mission development - bids in preparation for 2 yr development to bring ruggedization of penetrator subsystems and instruments up to TRL 5. 4.Mission – currently in discussion with BNSC and NASA

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Finally… For further information or see …the MoonLITE penetrators have the potential to make major contributions to lunar science. Ian Crawford, 2007.

ILEWG-9 Conference, Sorrento, Oct 22-26, End -

ILEWG-9 Conference, Sorrento, Oct 22-26, Science & ISRU Objectives 3 Far side lunar base ? –Characterize water, volatiles, and astrobiologically related material at lunar poles. => Water is key to manned missions –Constrain origin, differentiation, 3d internal structure & far side crustal thickness of moon via a seismic network. –Investigate enigmatic strong surface seismic signals => identify potentially dangerous sites for lunar bases –Determine thermal & compositional differences at polar regions and far side. –Obtain ground truth for remote sensing instruments

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007MoonLITE Far side baseline: – descent camera – accelerometer – seismometers – geochemistry package – thermal package options: – mineralogy camera – radiation monitor – magnetometer etc..  Scientific Instruments (Total mass ~2kg)

ILEWG-9 Conference, Sorrento, Oct 22-26, 2007 Mission Lifetime Trade Study  1 year lifetime desired for seismic network  Power Supply – ~500Wh. Default is Batteries (~2kg) –Solar cells <- no good at poles –Fuel cells (not studied) –RTG (when available)  Power Usage – efficient communications, low power seismometer pre-event monitoring, low power systems.  Thermal Issues – heat loss, especially at poles where temperatures expected ~50-100K & unknown external material conductivity. –Insulation (surface coating, internal) –Parasitic heat loss through wires –RHUs (to heat batteries -> extend lifetime) –Fallback reduced (seismometer) lifetime at poles.