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
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.
Environment Spatially Independent: Spatially Dependent: Regolith physical properties Chemistry (major element) Dust Surface disturbance on landing Rock frequency Radiation Micrometeoroids Magnetic field*** Atmosphere** Surface charging / levitated dust* Lighting Thermal Topography Communication / Earth View Resources Science Commerce Flight Precision landing Delta V budget Approach over shadowed terrain These are the site discriminators.
What Really Needs to Be Measured at the Moon? Risk Reduction / Cost Control / Optimization Apollo-like Sortie Polar Geodetic control enabling Topography - enabling High-resolution imaging (hazards) - enhancing Non-Polar Nothing enabling High-resolution imaging (hazards) - enhancing Outpost Being There (Just land safely) Polar Topography - enabling Geodetic control enabling Lighting model enhancing High-resolution imaging - enhancing Non-Polar Nothing enabling High-resolution imaging enhancing Global Dust toxicity TBD Electrical charging TBD
Apollo 16: Station 10 ALSEP Regolith Physical Properties
Blowing Regolith - Apollo LM Descent Apollo 11 Initiate: 73-33 m (240-110 ) 75% Obscuration at Touchdown Material moved along surface deflected by rocks Apollo 12 Initiate: 53 m (175 ) Obscuration 12 m (40 ) Surface altered below 9-12 m altitude Apollo 14 Initiate: 33 m (110 ) Erosion of 10 cm 1 m SE of nozzle Apollo 15 Initiate: 45 m (150 ) Obscuration 18 m (60 ) Apollo 16 Initiate: 25 m (80 ) Block and small crater visible to surface Apollo 17 Initiate: 20 m (65 ) No obscuration Evidence of plume interaction with surface across 50 m 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. AS11-40-5920 AS12-47-6906 AS14-66-9261
Dust: <50 µm size fraction consists largely of impact produced glass complicated shapes, jagged edges, large surface area <20 micron size fraction: 20 wt % of soil Dust 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 micron A11-10084: 50% of particles are <0.1 micron A11-10084: >40% ultrafine (<100 nm) particles A17-70051: 50% of particles are <0.3 micron
What Really Needs to be Measured at the Moon? Outpost with Resource Utilization Resource distribution (ore characterization) H form, concentration, distribution in polar regions (lighted and shadowed) Highlands composition Pyroclastic composition Regolith physical properties Pyroclastic deposits Permanently shadowed Polar Topography - enabling Geodetic control enabling Lighting model enhancing High-resolution imaging - enhancing Non-Polar High-resolution imaging enhancing Global Dust toxicity TBD Electrical charging TBD
Lunar Robotic Precursor Program 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
Which Resources Are Important? Apollo 11 soil Mare Apollo 16 soil Highlands H 20-100 ppm 4-40 ppm He* 19-80 ppm 3-35 ppm Ar 1.3-12 ppm 0.7-3 ppm Xe 0.5-3.8 ppm 0.2-1 ppm C 100-200 ppm 30-280 ppm N 20-80 ppm 4-200 ppm K 1000-1800 ppm 380-1100 ppm P 480-650 ppm 130-1100 ppm S 660-1500 ppm 470-640 ppm F 75-520 ppm 27-105 ppm Cl 3-40 ppm 12-270 ppm * 4 He/ 3 He = ~ 2500 One cubic meter (1 m 3 ) 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)
Resource Exploitation Data for Decision in the Critical Path 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
Polar Objectives: Find and characterize resources that make exploration affordable and sustainable Lunar volatiles (e.g., H) Sunlight Landing site morphology Physical Properties Dust Oxidation Potential Radiation 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 environments Provide opportunities for industry, educational and international partners
Pyroclastic Deposits Gaddis et al. 2003 Pyroclastic deposits have high H content Apollo 17 orange glass and Apollo 15 green glass highly enriched in volatile elements Black glass contains illmenite enhanced H retention
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? Margot et al. Earth-based radar Clementine Bi-Static Experiment
Polar Light Mission Overview Develop common lander to land in sunlight near lunar pole to characterize environment and deposits Lander becomes standard design for delivery of future payloads Sunlight mission answers first-order questions about poles and provides ground truth for orbital sensing Concept of Operations Precision landing & hazard avoidance Characterize sun illumination over a seasonal cycle Direct measurement of neutron flux, soil hydrogen concentration in sunlit area for correlation with orbital mapping Biological radiation response characterization Characterize lunar dust and charging environment Possible micro-rover for near-field investigation (if funded separately) Picture/Diagram
Polar Dark Mission Overview Reference concept: fuel cell-powered rover, ranging > 25 km and obtaining > 22 subsurface measurements (each 1,000 m apart) to map and analyze polar volatiles Navigation by integration of coherent ranging with an overhead relay satellite, IMU, and perhaps terrain relative navigation Navigation by flash lamps and MER style hazard avoidance or 3-D scanning LIDAR RTG-powered options are lighter and offer extended life, but are more costly 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
Polar Dark Rover Dawes Crater Shadow in Earth-based radar images is Earth-shadow; entire crater floor is in sun-shadow Green NS pixels Red High Radar CPR Orange Permanent sunlight Blue line Rover traverse
Lander / Rover Concepts
ISRU Excavation Rover 1/10 th scale demo
RLEP-2 Lander Performance Summary Arch. 1 Arch. 3 Arch. 6 Arch. 7 Arch. 9C Arch. 9H Arch. 10 small cryo Payload Landed Mass (kg) 2200 2000 1800 1600 1400 1200 1000 800 600 400 200 0 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) MSL Viking 645 430, 450 296 Atlas 401 (3580 kg) Direct Landing, Hypergol + Solid LAT Orbit First, Hypergol Luna/ Lunokhod 2 Luna/ Lunokhod 1 Atlas 551 (6560 kg) Note: Added battery mass specific for crater rim mission during eclipse is counted as payload mass for this comparison (130-156 kg) 2000 3000 4000 5000 6000 7000 8000 9000 10000 1351 987 917 888 614 565 Injected Mass (kg) Orbit First, Cryogenic 2003 1622 1326 724 Delta IV H (9615 kg) Off Graph: Surveyor (1006, 41) MER (1063, 174) Apollo 15 (46,838, 4971) (Assumes ascent vehicle is landed payload)
Summary Precursor robotic missions to the Moon Better define the environment Reduces risk Increases efficiency Resource 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 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) Robotic missions: Provide early strategic information for human missions Key knowledge needed for human safety and mission success Infrastructure elements for eventual human use Data will be used to plan and execute human exploration of the Moon Resolve the unknowns of the lunar polar regions Knowledge of the environment temperature, lighting, etc. Resources/deposits composition and physical nature Terrain and surface properties - dust characterization Emplace support infrastructure navigation/communication, beacons, teleoperated robots Make exploration more capable and sustainable Emplace surface systems Demonstrate new technologies that will enable settlement Operational experience in lunar environment Create new opportunities for scientific investigation