Rationale of NASA Lunar Precursor Robotic Program (LPRP) … for the VSE (vs. I don’t need nuthin’ but a map) Jeff Plescia, Ben Bussey, Paul Spudis, Tony Lavoie Applied Physics Laboratory, Johns Hopkins University Marshall Space Flight Center October 23, 2007 ILEWG Meeting
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Rationale of NASA Lunar Precursor Robotic Program (LPRP)
… for the VSE
(vs. I don’t need nuthin’ but a map)
Jeff Plescia, Ben Bussey, Paul Spudis, Tony LavoieApplied Physics Laboratory, Johns Hopkins University
Marshall Space Flight Center
October 23, 2007ILEWG Meeting
Considerations
Objective: Establishment of outpost site for long-term occupation.“…sustained human presence on the Moon…”
Environmental considerations (lighting, thermal) may be paramount.
Resource potential may be important.
Scientific objectives not likely to be a driver.
International cooperation, commercial ventures, ….
Different from Apollo and Mars robotic missions.
Raison d’etre for lunar outpost must be established.It defines what characteristics are important.
Initiate: 73-33 m (240-110’)75% Obscuration at TouchdownMaterial moved along surface – deflected by rocks
Apollo 12Initiate: 53 m (175’)Obscuration 12 m (40’)Surface altered below 9-12 m altitude
Apollo 14Initiate: 33 m (110’)Erosion of 10 cm 1 m SE of nozzle
Apollo 15Initiate: 45 m (150’)Obscuration 18 m (60’)
Apollo 16Initiate: 25 m (80’)Block and small crater visible to surface
Apollo 17Initiate: 20 m (65’)No obscurationEvidence of plume interaction with surface across 50 m
AS11-40-5920 AS12-47-6906 AS14-66-9261
The amount of material disturbed by the LM descent engine is a strong function of the approach trajectory and speed. Oblique trajectory causes the least disturbance of the surface. Vertical descent ( A15) caused the most disturbance.
DustDust: <50 µm size fraction
consists largely of impact produced glasscomplicated shapes, jagged edges, large surface area<20 micron size fraction: 20 wt % of soil
Different composition from bulk regolith.
Impact generated glass and nano-phase Fe increase with decreasing grain size.~80 wt. % at sizes <10 micron
Taylor et al. (2007) and Liu et al. (2007) data on size-frequency distribution of dust-sized material (20 microns-20 nm).
Two samples 10084-70051 both display peaks at 100-200 nm>95% are <2 micronA11-10084: 50% of particles are <0.1 micronA11-10084: >40% ultrafine (<100 nm) particlesA17-70051: 50% of particles are <0.3 micron
What Really Needs to be Measured at the Moon?
Outpost with Resource UtilizationResource distribution (ore characterization)
H form, concentration, distribution in polar regions (lighted and shadowed)
Undertake robotic lunar exploration missions that will return data to advance our knowledge of the lunar environment and allow United States (US) exploration architecture objectives to be accomplished earlier and with less cost through application of robotic systems. LPRP will also reduce risk to crew and maximize crew efficiency by accomplishing tasks through precursor robotic missions, and by providing assistance to human explorers on the Moon.
Orbital mapping and reconnaissance with Chandrayaan, LRO, et al.
Probing the surface with impactors (LCROSS)
….
Exploring and prospecting future habitation sites with surface landers and rovers
Emplacing orbital communications and navigation assets to support future missions
One cubic meter (1 m3) of lunar regolith contains enough hydrogen, carbon, nitrogen, potassium, and other trace elements to make lunch for two – two cheese sandwiches on rye, two colas (flavored with real sugar, although there’s enough Cl to sweeten it with Splenda instead), and two large plums.
(credit: Larry Taylor)
Water ice in shadowed regions of both poles
Extract oxygen, metals from lunar materials for construction, propellant
Recover solar-wind gases (e.g., hydrogen and other volatiles) implanted on lunar regolith
Collect solar energy with photoelectric arrays built from lunar materials and beam energy to Earth or cislunar space
Resource Exploitation –Data for Decision in the Critical Path
Polar
Objectives:
Find and characterize resources that make exploration affordable and sustainable
Lunar volatiles (e.g., H)Sunlight
Landing site morphologyPhysical PropertiesDustOxidation PotentialRadiation Environment / Shielding
Field test new equipment, technologies and approaches (e.g., dust and radiation mitigation)
Support demonstration, validation, and establishment of heritage of systems for use on human missions
Gain operational experience in lunar environmentsProvide opportunities for industry, educational and
international partners
Gaddis et al. 2003
Pyroclastic deposits have high H contentApollo 17 orange glass and Apollo 15 green
glass highly enriched in volatile elementsBlack glass contains illmenite – enhanced H
retention
Pyroclastic Deposits
Resources - H
Elphic modeling voodoo – Using radar topography, calculate shadowed areas, allow illuminated regions to have up to 200 ppm H, shadowed areas have whatever is necessary to match neutron signature.
Concentration is a function of shadow area and whether H is uniformly distributed. Concentrations could be higher if shadowed areas not uniformly filled.
Resources - Ice?
Clementine Bi-Static ExperimentMargot et al. Earth-based radar
Polar Light MissionOverviewDevelop common lander to land in sunlight near lunar
pole to characterize environment and depositsLander becomes standard design for delivery of future
payloadsSunlight mission answers first-order questions about
poles and provides ground truth for orbital sensing
Concept of Operations
Precision landing & hazard avoidanceCharacterize sun illumination over a seasonal cycleDirect measurement of neutron flux, soil hydrogen
concentration in sunlit area for correlation with orbital mapping
Biological radiation response characterizationCharacterize lunar dust and charging environmentPossible micro-rover for near-field investigation (if
funded separately)Picture/Diagram
Polar Dark Mission
Concept of Operations
Rover delivered directly to the crater floor by the lander (which expires shortly after rover egress)
Rover traverses to selected sites obtaining ground penetrating radar and neutron spectrometer profiles along the way
Sampling at predetermined site, rover drills and samples material approximately every 50 cm to a maximum depth of 2 m
On-board analysis of volatile content and composition
OverviewReference concept: fuel cell-powered rover, ranging > 25 km and obtaining > 22 subsurface measurements (each 1,000
m apart) to map and analyze polar volatilesNavigation by integration of coherent ranging with an overhead relay satellite, IMU, and perhaps terrain relative
navigationNavigation by flash lamps and MER style hazard avoidance or 3-D scanning LIDARRTG-powered options are lighter and offer extended life, but are more costly
Green – NS pixelsRed – High Radar CPROrange – “Permanent” sunlightBlue line – Rover traverse
Dawes Crater
Shadow in Earth-based radar images is Earth-shadow; entire crater floor is in sun-shadow
Range of values represents range of payload capacity depending on:• Trajectory approach• Mass growth from CBE (0-25%)• Whether relay satellite is co-launched (Architectures 1,9)• Propulsion selected for lander• Whether lander hops out of crater (Architecture 10)
Note: Added battery mass specific for crater rim mission during eclipse is counted as payload mass for this comparison (130 - 156 kg)
Off Graph:• Surveyor (1006, 41)• MER (1063, 174)• Apollo 15 (46,838, 4971) (Assumes ascent vehicle is landed payload)
Delta IV H (9615 kg)Atlas 551
(6560 kg)
Atlas 401(3580 kg)
Direct Landing, Hypergol + Solid
Orbit First, Hypergol
Orbit First, C
ryogenic
Luna/Lunokhod 1
Luna/Lunokhod 2
Viking
645
430, 450
1351
888
565614
987
917
2003
1326
1622
724
296
LAT
Summary
Precursor robotic missions to the Moon Better define the environment
Reduces riskIncreases efficiencyResource trades (e.g., proximity to sunlight for power and water for fuel)
Don’t want to have to move the outpost.
Most important objectives:Characterize new or poorly understood
processes and environments (e.g., lunar poles)
Pre-reconnaissance of targets for future human exploration
Resource prospecting
Robotic missions have other important programmatic uses beyond science; scientific exploration can be opportunistic
Robotic Precursor Missions
Robotic missions:Provide early strategic information for human missions
Key knowledge needed for human safety and mission successInfrastructure elements for eventual human useData will be used to plan and execute human exploration of the
Moon
Resolve the unknowns of the lunar polar regionsKnowledge of the environment – temperature, lighting, etc.Resources/deposits – composition and physical natureTerrain and surface properties - dust characterizationEmplace support infrastructure – navigation/communication,
beacons, teleoperated robots
Make exploration more capable and sustainableEmplace surface systemsDemonstrate new technologies that will enable settlementOperational experience in lunar environmentCreate new opportunities for scientific investigation
“Starting no later than 2008, initiate a series of robotic missions to the Moon to prepare for and support future human exploration activities” (NSPD-31)