Title: Technical Trade Studies for a Lunar Penetrator Mission
1Technical Trade Studies for a Lunar Penetrator
Mission
Alan Smith1, Rob Gowen1, Yang Gao2, and Phil
Church6
2Contents
- Introduction to Penetrators
- MoonLITE Mission
- Technical Trade Studies
- Program Status
- Summary Conclusions
3What are kinetic penetrators ?
- Low mass projectiles 2-13Kg
- High impact speed 200-500 m/s
- Very tough 10-50kgee
- Penetrate surface few metres
- Perform science from below surface
4- History ?
- No successful mission yet.
- DS2 failed alongside soft lander.
- Mars96 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!
5Impact Test
6MoonLITE
Polar comms orbiter
3
- 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 10-15 kg penetrator 20-25 kg
de-orbit and attitude control). - Landing sites Globally spaced Far side, Polar
region(s), One near an Apollo landing site for
calibration. - Duration gt1 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
4
2
1
7MoonLITE Payload Key Objectives
8MoonLITE
9Consider some Technical Challenges
- Descent - deceleration, ACS
- Structure material, design
- Comms regolith, aerial
- Lifetime power, thermal
(Others include data handling, impact physics,
instruments..)
10Descent Systems Trade Study
- Desire-
- Landing ellipse not too large
- Impact angle lt45? to vertical
- Attack angle lt8?
- Impact speed 300ms
- Constraints
- mass
- impact site contamination
PDS Payload Delivery System Baseline 13Kg
penetrator
Penetrator separation system
ACS
Spacecraft ejection system
De-orbit Motor
- PDS land away from penetrator
- Orientation disturbance of penetrator
- Ensure orientation
- Attack angle control (mass)
- Penetrator mass
- Fuel type (mass)
- Impact angle
Does not have to survive impact
11Penetrator Structure Trade Study
- Require-
- Survive impact
- Ensure penetration depth 2-5m
- Restrict deflection during impact
- Minimise forces on internal systems
- Constraints
- mass
- impact site contamination
Penetrator Baseline 13kg 120mm diameter 60cm
long
Material
Design
- Payload gt size gt mass
- Diam/length ratio (impact deflection)
- Penetration depth (shape)
- Strength (apertures)
- Integratibility/harnessing
- gt thermal
is the only material which could allow heat
flow without external thermal insulation
12Communications Trade Study
- Require-
- Survive impact
- Communicate to orbit from beneath regolith
- Receive commands from orbit
- Possibly help with azimuthal orientation
Communications Baseline Beagle2 Melacom,
6W.hr. One 90sec contact/15days Avg tel
30kbits/day Avg cmd low.
Issues
technology
- Power vs Regolith attenuation (ice/volatiles,
penetration depth ?) - Communication strategies gt power
- Commanding gt seismometer event
- coordination
- Receiver/transmitter
- Patch aerial (polarisation)
- Trailing antennae ? ( aid heat flow
measurement)
13Power-Thermal Trade Study
Power Baseline 500Wh, 2kg batteries solar cells
not at poles fuel cells not studied RPG
when available
- Constraints
- mass/size
- rugged
Desire mission lifetime ?1year for seismometry
RHUs Keep batteries warm
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 -gt reduce seismometer lifetime at poles
14MoonLITE Mission Status
- Penetrator Design baseline agreed.
- Full-scale structure impact trial Scheduled
March 2008 - Pre-mission development - bids in preparation for
2 yr development to bring ruggedization of
penetrator subsystems and instruments up to TRL
5. - Mission currently in discussion with BNSC and
NASA
15Finally
-
- For further information email as_at_mssl.ucl.ac.uk
- or see
http//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.
16- End -
17Science ISRU Objectives
3
- Characterize water, volatiles, and
astrobiologically related material at lunar
poles. gt 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 gt identify potentially dangerous
sitesfor lunar bases - Determine thermal compositional differences at
polar regions and far side. - Obtain ground truth for remote sensing instruments
4
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18MoonLITE
3
- Scientific Instruments (Total mass 2kg)
Far side
- baseline
- descent camera
- accelerometer
- seismometers
- geochemistry package
- thermal package
-
- options
- mineralogy camera
- radiation monitor
- magnetometer
- etc..
4
2
1
19Mission Lifetime Trade Study
- 1 year lifetime desired for seismic network
- Power Supply 500Wh. Default is Batteries
(2kg) - Solar cells lt- 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 -gt extend lifetime)
- Fallback reduced (seismometer) lifetime at poles.