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SMD & HEOMD Priorities

The Lunar Water Assessment, Transport, Evolution, and Resource (WATER) Small Satellite Mission Concept. C.A. Hibbitts 1 , L. Burke 2 , B. Clyde 1 , B. Cohen 3 , J. Dankanich 4 , D. Hurley 1 , R. Klima 1 , D. Lawrence 1 , A. Mirantes 1 , D. Moessner 1 , J. Plescia 1 , J. Sunshine 5

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SMD & HEOMD Priorities

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  1. The Lunar Water Assessment, Transport, Evolution, and Resource (WATER) Small Satellite Mission Concept C.A. Hibbitts1, L. Burke2, B. Clyde1, B. Cohen3, J. Dankanich4, D. Hurley1, R. Klima1, D. Lawrence1, A. Mirantes1, D. Moessner1, J. Plescia1, J. Sunshine5 1JHU-APL, 2NASA GRC, 3NASA GSFC, 4NASA MSFC, 5Univ. of Md. karl.hibbitts@jhuapl.edu

  2. SMD & HEOMD Priorities UNCLASSIFIED The 2013 – 2022 NRC Decadal Survey: “Understand the composition of distribution of volatile chemical compounds” and several “Important Questions”: “How are volatile elements and compounds distributed, transported, and sequestered in near-surface environments on the surfaces of the Moon and Mercury?” “What fractions of volatiles were outgassed from those planets’ interiors, and what fractions represent late meteoritic and cometary infall?” Lunar Resources • Lunar Strategic Knowledge Gaps (SKGs) related to Lunar resources • 1C. Regolith 2: Quality / quantity / distribution / form of H species and other volatiles in nonpolar mare and highlands regolith. • 1D. Polar Resources 6: Composition, form and distribution of polar volatiles. • 1D. Polar Resources 7: Temporal variability and movement dynamics of surface-correlated OH and H2O deposits towards PSR retention. • 1E Composition / volume / distribution / form of pyroclastics / dark mantle deposits and characteristics of associated volatiles.

  3. Mission Concept Notional Mission Schedule: Project Phase A - D: 3 yr Transit GTO to Lunar Orbit ~ 3 mo Transition to low periapsis: ~ 2 mo Science Ops: 6 mo Phase A – E Duration: 4 yrs

  4. Science Objectives UNCLASSIFIED Evaluate mission, payload and CONOPS feasible with a small Lunar orbiter to characterize the water on the Moon. Sources (solar wind, micrometeorites,…. Science Objectives: What are the chemical form(s) of water on the Moon, including the PSRs, and how are they distributed spatially? How does surficial lunar water evolve over space and time? Is solar wind implantation responsible for the OH on the illuminated Moon? & Sinks PSRs, exospheric escape, ,…. Pieters et al., 2009 Lawrence et al., 2006

  5. Instruments UNCLASSIFIED Mapping Surficial Water and Hydroxyl Mapping Near-Surface Polar Hydrogen MIMSI Mid-Infrared Multi-Spectral Imager WattIR Active Multiband IR Reflectometer NS Neutron Spectrometer

  6. Mission Trajectory (from GTO) 15 km x 1000 km Polar LLO (Perilune over S. Pole) 201 days thrusting 24 days coasting coast burn GEO to Weakly Captured Lunar Orbit = 177 days GTO Spiral-In: 48 days

  7. Mission Trajectory (Lunar insertion) • Lunar Frozen Orbit (Rp = 45 to 75km) • a = 1850km, e = 0.035, • i = 90º, aop = 265.189º Co-Manifested with Lunar Orbiter Nominal TLI minimizes LOI to insert into 100km LPO EP System Power: 800 W EP Thruster Strings: 1+1 TOF to Lunar vicinity = 79 days Launch C3 = -2.11 km2/s2 Pre-LOI C3 = 0.705 km2/s2 Spiral-In TOF = 94 days 29.6 kg coast burn 1850km Frozen Orbit

  8. Concept of Operations Orbit: 2.65 hours period 1000km apoapsis over NP ~ 15 km periapsis over SP 90o inclination, with an argument of periapsis within 5o of SP Challenges: Maintaining argument of peripsis Maintaining altitude control for c/a Eclipse: Lunar < 50 min. Earth&Lunar combo: < 3.75 hours Science Operations: • ~ 1Gbit/orbit • Remote sensing instruments on as much as possible. • Active illumination (radar, laser) only near c/a.

  9. Challenges • Assumptions: • 4 RWs • 6 sun sensors (always on) • 3 star trackers (always on) • LNA always on • PDU at half power nonop • SSPA off at nonop • Avionics always on • NS always on • WATIR cyrocooler always on • IMU always on • One rcvr always on • WATIR 25% efficient • SADA and SAE off nonop Thermal Challenges: nonop cold (eclipse): 78 W idle op: 172 W instrument ops: 285 W thruster ops: 373 W Power Challenges: Need 8 m2 of solar panel to power the necessarily redundant Busek engines Trajectory Challenges Long transition time. Lots of deltaV Only a few are stable

  10. Spacecraft UNCLASSIFIED 3-axis stabilized with instruments on nadir facing deck Solar-electric propulsion

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