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THE CHARACTERIZATION OF THE MOON'S EXOSPHERE WITH MEASUREMENTS FROM ORBIT IS A PRIME SCIENCE OBJECTIVE OF NASA'S LUNAR ATMOSPHERE AND DUST ENVIRONMENT EXPLORER (LADEE) MISSION. IN THIS PROPOSAL WE FOCUS ON DEVELOPING TOOLS THAT WILL SUPPORT LADEE OPERATIONS PLANNING AND ENABLE ANALYSIS OF DATA WHEN THEY BECOME AVAILABLE IN 2013. WE PROPOSE AN AUTOMATED METHOD GUIDED BY EXOSPHERIC PARTICLE TRANSPORT MODELS THAT WILL DERIVE 3D-SPATIAL MAPS OF LUNAR EXOSPHERIC EJECTA FROM ULTRAVIOLET/VISIBLE (UVS) LINE-OF-SIGHT MEASUREMENTS OF RESONANT-SCATTERED LIGHT. A PRELIMINARY METHOD APPLIED TO MEASUREMENTS OBTAINED BY MESSENGER DURING ITS THIRD MERCURY FLYBY SUGGESTS THAT A TOMOGRAPHIC APPROACH CAN REVEAL IMPORTANT CLUES ABOUT THE INFLUENCE OF DIFFERENT SOURCE FACTORS THAT GENERATE COLLISIONLESS EXOSPHERES. WE PROPOSE TO ADD PARTICLE TRANSPORT MODELS TO THIS METHOD IN ORDER TO GUIDE THE INVERSIONS AND REDUCE THE UNCERTAINTIES IN THE RECONSTRUCTED STRUCTURE. WE WILL VARY ASSUMPTIONS ABOUT HOW PARTICLES ARE LAUNCHED FROM THE SURFACE IN AGREEMENT WITH WHAT HAS BEEN HYPOTHESIZED IN THE LITERATURE. HYPOTHESIZED SOURCES INCLUDE PHOTONSTIMULATED DESORPTION THERMAL VAPORIZATION SOLAR WIND SPUTTERING MICROMETEOROID VAPORIZATION AND MOLECULAR DISSOCIATION. LOSS PROCESSES THAT WILL BE TREATED INCLUDE BUT ARE NOT LIMITED TO PHOTOIONIZATION AND STICKING TO THE SURFACE. THE PROPOSED PHYSICS-GUIDED INVERSION METHODS CAN HELP: 1)DETERMINE THE SPATIAL AND TEMPORAL MORPHOLOGY OF THE LUNAR EXOSPHERE PARTICULARLY OF NA AND K THAT WILL BE MEASURED BY LADEE UVS WITH HIGH SIGNAL-TO-NOISE RATIO; AND 2) RELATE EXOSPHERIC STRUCTURE TO COMPOSITIONAL VARIATIONS ACROSS THE SURFACE. WE DEMONSTRATE WITH A BENCHMARK SIMULATION THAT THE PROPOSED COUPLING OF TRANSPORT MODELS WITH TOMOGRAPHIC METHODS CAN BE IMPLEMENTED IN A COMPUTATIONALLY EFFICIENT MANNER. THEREFORE THEY PROMISE TO HELP ANALYZE THE VOLUME OF DATA EXPECTED FROM LADEE. OUR PROPOSAL ANSWERS TO THE TOPICAL STUDY AREA "DEVELOPMENT COMPOSITION AND PHYSICS OF THE MOON'S EXOSPHERE" UNDER FUNDAMENTAL LUNAR SCIENCE OF THE LASER PROGRAM. THE PROPOSED WORK ALSO SUPPORTS OBJECTIVES OF APPLIED SCIENCE BECAUSE ADVANCED MODELS OF EXOSPHERIC NA AND K PRODUCED IN THE FIRST YEAR OF THIS WORK CAN INFORM THE LADEE PLANNING OF OPERATIONS FOR TWO SPECIES THAT WE KNOW UVS WILL SPATIALLY RESOLVE. FINALLY OUR RESEARCH HAS WIDER APPEAL BECAUSE IT SUPPORTS THE ANALYSIS OF SCIENTIFIC DATA FROM OTHER MISSIONS AROUND THE MOON AND ELSEWHERE (E.G. MESSENGER).

$158,533FY2014National Aeronautics and Space AdministrationNASA

University Of Maryland Baltimore County, Baltimore MD

Investigators

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THE CHARACTERIZATION OF THE MOON'S EXOSPHERE WITH MEASUREMENTS FROM ORBIT IS A PRIME SCIENCE OBJECTIVE OF NASA'S LUNAR ATMOSPHERE AND DUST ENVIRONMENT EXPLORER (LADEE) MISSION. IN THIS PROPOSAL WE FOCUS ON DEVELOPING TOOLS THAT WILL SUPPORT LADEE OPERATIONS PLANNING AND ENABLE ANALYSIS OF DATA WHEN THEY BECOME AVAILABLE IN 2013. WE PROPOSE AN AUTOMATED METHOD GUIDED BY EXOSPHERIC PARTICLE TRANSPORT MODELS THAT WILL DERIVE 3D-SPATIAL MAPS OF LUNAR EXOSPHERIC EJECTA FROM ULTRAVIOLET/VISIBLE (UVS) LINE-OF-SIGHT MEASUREMENTS OF RESONANT-SCATTERED LIGHT. A PRELIMINARY METHOD APPLIED TO MEASUREMENTS OBTAINED BY MESSENGER DURING ITS THIRD MERCURY FLYBY SUGGESTS THAT A TOMOGRAPHIC APPROACH CAN REVEAL IMPORTANT CLUES ABOUT THE INFLUENCE OF DIFFERENT SOURCE FACTORS THAT GENERATE COLLISIONLESS EXOSPHERES. WE PROPOSE TO ADD PARTICLE TRANSPORT MODELS TO THIS METHOD IN ORDER TO GUIDE THE INVERSIONS AND REDUCE THE UNCERTAINTIES IN THE RECONSTRUCTED STRUCTURE. WE WILL VARY ASSUMPTIONS ABOUT HOW PARTICLES ARE LAUNCHED FROM THE SURFACE IN AGREEMENT WITH WHAT HAS BEEN HYPOTHESIZED IN THE LITERATURE. HYPOTHESIZED SOURCES INCLUDE PHOTONSTIMULATED DESORPTION THERMAL VAPORIZATION SOLAR WIND SPUTTERING MICROMETEOROID VAPORIZATION AND MOLECULAR DISSOCIATION. LOSS PROCESSES THAT WILL BE TREATED INCLUDE BUT ARE NOT LIMITED TO PHOTOIONIZATION AND STICKING TO THE SURFACE. THE PROPOSED PHYSICS-GUIDED INVERSION METHODS CAN HELP: 1)DETERMINE THE SPATIAL AND TEMPORAL MORPHOLOGY OF THE LUNAR EXOSPHERE PARTICULARLY OF NA AND K THAT WILL BE MEASURED BY LADEE UVS WITH HIGH SIGNAL-TO-NOISE RATIO; AND 2) RELATE EXOSPHERIC STRUCTURE TO COMPOSITIONAL VARIATIONS ACROSS THE SURFACE. WE DEMONSTRATE WITH A BENCHMARK SIMULATION THAT THE PROPOSED COUPLING OF TRANSPORT MODELS WITH TOMOGRAPHIC METHODS CAN BE IMPLEMENTED IN A COMPUTATIONALLY EFFICIENT MANNER. THEREFORE THEY PROMISE TO HELP ANALYZE THE VOLUME OF DATA EXPECTED FROM LADEE. OUR PROPOSAL ANSWERS TO THE TOPICAL STUDY AREA "DEVELOPMENT COMPOSITION AND PHYSICS OF THE MOON'S EXOSPHERE" UNDER FUNDAMENTAL LUNAR SCIENCE OF THE LASER PROGRAM. THE PROPOSED WORK ALSO SUPPORTS OBJECTIVES OF APPLIED SCIENCE BECAUSE ADVANCED MODELS OF EXOSPHERIC NA AND K PRODUCED IN THE FIRST YEAR OF THIS WORK CAN INFORM THE LADEE PLANNING OF OPERATIONS FOR TWO SPECIES THAT WE KNOW UVS WILL SPATIALLY RESOLVE. FINALLY OUR RESEARCH HAS WIDER APPEAL BECAUSE IT SUPPORTS THE ANALYSIS OF SCIENTIFIC DATA FROM OTHER MISSIONS AROUND THE MOON AND ELSEWHERE (E.G. MESSENGER). · GrantIndex