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

Technical Trade Studies for a Technical Trade Studies for a Lunar Penetrator MissionLunar Penetrator Mission

Alan SmithAlan Smith11, , Rob GowenRob Gowen11, Yang Gao, Yang Gao22, and Phil , and Phil ChurchChurch66

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ContentsContents

Introduction to PenetratorsIntroduction to Penetrators MoonLITE MissionMoonLITE Mission Technical Trade StudiesTechnical Trade Studies Program StatusProgram Status Summary & ConclusionsSummary & Conclusions


What are kinetic penetrators ?What are kinetic penetrators ?

– Low mass projectiles Low mass projectiles ~2-13Kg ~2-13Kg

– High impact speed High impact speed ~ 200-500 m/s~ 200-500 m/s

– Very tough Very tough ~10-50kgee~10-50kgee

– Penetrate surface Penetrate surface ~ few metres~ few metres

– Perform science Perform science from below surfacefrom below surface

Penetrator

Point of Separation

Payload Instruments

Detachable Propulsion Stage

PDS (Penetrator

Delivery System)


History ?History ?– No successful mission yet.No successful mission yet.– DS2 failed alongside soft lander.DS2 failed alongside soft lander.– Mars’96 spacecraft failed to Mars’96 spacecraft failed to

leave Earth orbit.leave Earth orbit.– Lunar-A cancelled but maybe fly Lunar-A cancelled but maybe fly

on Lunar-Glob.on Lunar-Glob.

Feasibility ?Feasibility ?– Lunar-A and DS2 space qualified.Lunar-A and DS2 space qualified.– Military have been successfully Military have been successfully

firing instrumented projectiles for firing instrumented projectiles for many years to comparable levels many years to comparable levels of gee forces into sand, concrete of gee forces into sand, concrete and steel.and steel.

– 40,000gee qualified electronics 40,000gee qualified electronics exist (and re-used)exist (and re-used)

When asked to describe the When asked to describe the condition of a probe that had condition of a probe that had

impacted 2m of concrete at 300 m/s impacted 2m of concrete at 300 m/s a UK expert described the device as a UK expert described the device as

‘a bit scratched’!‘a bit scratched’!


Impact TestImpact Test


MoonLITEMoonLITE Delivery and Comms SpacecraftDelivery and Comms Spacecraft (Orbiter).(Orbiter).

Deliver penetrators to ejection orbit. Deliver penetrators to ejection orbit. provide pre-ejection health status, provide pre-ejection health status, and relay communications.and relay communications.

Orbiter PayloadOrbiter Payload:: 4 Descent Probes 4 Descent Probes (each containing 10-15 kg penetrator (each containing 10-15 kg penetrator + 20-25 kg de-orbit and attitude + 20-25 kg de-orbit and attitude control).control).

Landing sites:Landing sites: Globally spaced Globally spaced Far side, Polar region(s), One near Far side, Polar region(s), One near an Apollo landing site for calibration.an Apollo landing site for calibration.

DurationDuration:: >1 year for seismic network. >1 year for seismic network. Other science does not require so long Other science does not require so long (perhaps a few Lunar cycles for heat flow (perhaps a few Lunar cycles for heat flow and volatiles much less).and volatiles much less).

Penetrator DesignPenetrator Design:: Single Body for Single Body for simplicity and risk avoidance. Battery powered simplicity and risk avoidance. Battery powered with comprehensive power saving techniqueswith comprehensive power saving techniques..

3

2

1

4

Far side

Polar commsorbiter


MoonLITE MoonLITE Payload & Key ObjectivesPayload & Key Objectives

AccelerometerAccelerometer - Regolith mechanical strength- Regolith mechanical strength

- Depth of penetration- Depth of penetration

Seismometers Seismometers

(& tiltmeter)(& tiltmeter)

- 3D structure of Lunar interior and core.- 3D structure of Lunar interior and core.

- Characterize enigmatic strong surface quakes- Characterize enigmatic strong surface quakes

=> Identify potentially dangerous sites for lunar bases=> Identify potentially dangerous sites for lunar bases

Thermal Thermal - Presence of conducting volatiles- Presence of conducting volatiles

- Heat flow -> Internal composition of moon.- Heat flow -> Internal composition of moon.

GeochemistryGeochemistry - Polar water and volatiles Polar water and volatiles

=> Water is vital to manned missions=> Water is vital to manned missions

- Astrobologically related material- Astrobologically related material

+ Options+ Options: mineralogy : mineralogy camera, radiation camera, radiation monitor, magnetometermonitor, magnetometer

Minerals at poles and farside.Minerals at poles and farside.

Internal radiative composition. Internal radiative composition.

Remanent magnetismRemanent magnetism

Total Mass ~2KgTotal Mass ~2Kg


MoonLITEMoonLITE


Consider some Consider some Technical Challenges Technical Challenges

Descent Descent - - deceleration,deceleration, ACSACS

Structure Structure – material, design– material, design

CommsComms – regolith, aerial– regolith, aerial

Lifetime Lifetime – power, thermal– power, thermal

(Others include data handling, impact physics, instruments..)


Descent Systems Trade StudyDescent Systems Trade StudyPDS

Payload Delivery SystemBaseline ~ 13Kg penetrator

Spacecraft ejectionsystem

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 sizeDoes not have to survive impact


Penetrator Structure Trade StudyPenetrator Structure Trade StudyPenetrator

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

Material

MaterialMaterial Subsystems Subsystems /payload mass/payload mass

Penetrator Penetrator total masstotal mass

SteelSteel 6.5 Kg6.5 Kg 27.4 Kg27.4 Kg

AluminiumAluminium 7.4 Kg7.4 Kg 13.0 Kg13.0 Kg

TitaniumTitanium 8.5 Kg8.5 Kg 10.8 Kg10.8 Kg

Carbon FibreCarbon Fibre** 7.3 Kg7.3 Kg 10.5 Kg10.5 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


Communications Trade StudyCommunications Trade Study

CommunicationsBaseline: Beagle2 Melacom,

6W.hr. One 90sec contact/15daysAvg 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)


Power-Thermal Trade StudyPower-Thermal Trade StudyPower

Baseline ~500Wh, 2kg batteries solar cells – not at polesfuel cells – not studiedRPG – 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

RHUsKeep batteries warm

Desire: mission lifetime

1year for seismometry

Constraints:• mass/size• rugged


MoonLITE Mission StatusMoonLITE Mission Status

1.1. Penetrator Design Penetrator Design – baseline agreed.– baseline agreed.

2.2. Full-scale structure impact trial Full-scale structure impact trial – Scheduled – Scheduled March 2008March 2008

3.3. Pre-mission developmentPre-mission development - bids in preparation - bids in preparation for 2 yr development to bring ruggedization of for 2 yr development to bring ruggedization of penetrator subsystems and instruments up to penetrator subsystems and instruments up to TRL 5.TRL 5.

4.4. Mission Mission – currently in discussion with BNSC and – currently in discussion with BNSC and NASANASA


Finally…Finally…

For further information email: For further information email: [email protected]@mssl.ucl.ac.uk

or seeor see

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

…the MoonLITE penetrators have the potential to make major contributions to

lunar science. Ian Crawford, 2007.


- End -- End -


2

1

4

Science & ISRU Objectives3

Far side

lunar base ?

– Characterize water, volatiles, and Characterize water, volatiles, and astrobiologically related material at astrobiologically related material at lunar poles. lunar poles. => Water is key to manned missions=> Water is key to manned missions

– Constrain origin, differentiation, 3d Constrain origin, differentiation, 3d internal structure & far side crustal internal structure & far side crustal thickness of moon via a seismic thickness of moon via a seismic network.network.

– Investigate enigmatic strong surface Investigate enigmatic strong surface seismic signals seismic signals => identify potentially dangerous sites=> identify potentially dangerous sitesfor lunar basesfor lunar bases

– Determine thermal & compositional Determine thermal & compositional differences at differences at polar regionspolar regions and and far sidefar side..

– Obtain ground truth for remote sensing instrumentsObtain ground truth for remote sensing instruments


MoonLITEMoonLITE3

2

1

4

Far side

baseline: – descent camera

– accelerometer– seismometers – geochemistry package – thermal package

options: – mineralogy camera – radiation monitor – magnetometer etc..

Scientific Instruments (Total mass ~2kg)


Mission Lifetime Trade StudyMission Lifetime Trade Study 1 year lifetime desired for seismic network1 year lifetime desired for seismic network Power Supply – Power Supply – ~500Wh. Default is Batteries (~2kg)~500Wh. Default is Batteries (~2kg)

– Solar cells <- no good at polesSolar cells <- no good at poles– Fuel cells (not studied)Fuel cells (not studied)– RTG (when available)RTG (when available)

Power UsagePower Usage – efficient communications, low power seismometer – efficient communications, low power seismometer pre-event monitoring, low power systems.pre-event monitoring, low power systems.

ThermalThermal IssuesIssues – heat loss, especially at poles where temperatures – heat loss, especially at poles where temperatures expected ~50-100K & unknown external material conductivity.expected ~50-100K & unknown external material conductivity.– Insulation (surface coating, internal)Insulation (surface coating, internal)– Parasitic heat loss through wiresParasitic heat loss through wires– RHUs (to heat batteries -> extend lifetime)RHUs (to heat batteries -> extend lifetime)– Fallback reduced (seismometer) lifetime at poles.Fallback reduced (seismometer) lifetime at poles.

Documents

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