THE ROSETTA MISSION ACCOMPLISHED AN UNPRECEDENTED AND SUCCESSFUL 2-YEAR STUDY OF COMET 67P/CHURYUMOV-GERASIMENKO AS IT ORBITED THE SUN BEGINNING AT ~3.8 AU BEFORE PERIHELION FOLLOWING IT THROUGH ITS ACTIVE PERIOD AROUND PERIHELION AT 1.24 AU AND THEN OUT AGAIN AFTER PERIHELION AT ~3.8 AU. WHILE MANY THINGS HAVE BEEN LEARNED BY THE FIRST ROUND OF ANALYSES OF THE MEASUREMENTS OBTAINED MUCH IS LEFT TO BE INVESTIGATED IN THE VAST WEALTH OF DATA OBTAINED AND ARCHIVED. WE DEVELOPED A SPHERICAL HARMONICS INVERSION METHOD THAT WAS ORIGINALLY APPLIED TO ROSINA DFMS MASS SPECTROMETER MEASUREMENTS TO OBTAIN POTENTIAL SURFACE ACTIVITY MAPS OF H2O CO2 CO AND O2 ON THE NUCLEUS OF COMET 67P (FOUGERE ET AL. 2016A&B) AVERAGED OVER LARGE TIME SLICES OF THE MISSION. WE DEMONSTRATED SOME SUCCESS IN SYNTHESIZING VIRTIS-M SPECTRAL IMAGES AND VIRTIS-H SPECTRA OF H2O AND CO2 DENSITIES USING THE SURFACE POTENTIAL DISTRIBUTION DERIVED FROM IN SITU MASS SPECTROMETER MEASUREMENTS ALONG WITH OUR FULLY-KINETIC ADAPTIVE MESH PARTICLE SIMULATOR (AMPS) MODEL FOR THE COMA THAT USES THE TECHNIQUE CALLED DIRECT SIMULATION MONTE CARLO. WE HAVE SINCE ADAPTED THE INVERSION METHOD TO INGEST COLUMN DENSITY MAPS AND VALUES FROM IMAGING DATA RATHER THAN IN SITU DENSITY MEASUREMENTS AND ARE ABLE TO DERIVE POTENTIAL SURFACE ACTIVITY MAPS. HERE WE PROPOSE TO ANALYZE A SIGNIFICANT FRACTION OF H2O AND CO2 DISTRIBUTIONS DERIVED FROM VIRTISM SPECTRAL IMAGES AND VIRTIS-H SPECTRA USING SPHERICAL HARMONICS INVERSION SCHEME. THE ONE ADVANTAGE OF VIRTIS REMOTE SENSING MAPS OVER DFMS DENSITIES IS THAT REMOTE SENSING MEASURES THE DISTRIBUTION OF GAS IN COMA VERY CLOSE TO THE NUCLEUS AT KILOMETER AND SUB-KILOMETER SCALES WHEREAS THE MASS SPECTROMETER MEASURES THE DISTRIBUTION OF GAS FAR FROM THE NUCLEUS (10-400 KM) WHERE DETAILED INFORMATION OF THE DISTRIBUTION OF THE SOURCE REGION AT THE NUCLEUS HAS BEEN SMEARED OUT. OUR MAJOR SCIENTIFIC GOALS ARE (1) TO DETERMINE THE POTENTIAL SURFACE ACTIVITY DISTRIBUTIONS OF H2O AND CO2 FROM THE NUCLEUS AT MUCH HIGHER SPATIAL RESOLUTION THAN POSSIBLE FROM MASS SPECTROMETER MEASUREMENTS (2) TO DETERMINE THE CHANGE IN SURFACE ACTIVITY DISTRIBUTION OF H2O AND CO2 AS A FUNCTION OF TIME OVER THE MISSION (3) TO INVESTIGATE THE APPARENT INCONSISTENCY OF WATER ABUNDANCES DURING THE FEW MONTHS AROUND PERIHELION IN MID-2015 BETWEEN MASS SPECTROMETER AND REMOTE SENSING INSTRUMENTS AS CONTRASTED WITH THE CONSISTENCY DURING THE FIRST ONE-THIRD OF THE MISSION FROM RENDEZVOUS THROUGH THE FIRST EQUINOX (4) TO CORRELATE THE DISTRIBUTIONS OF THESE MAJOR VOLATILE COMPONENTS WITH THE MORE STRUCTURED DISTRIBUTIONS OF DUST PRODUCTION AS SEEN IN OSIRIS IMAGES. ALL OF THE DATA FROM VIRTIS AND OSIRIS REQUIRED FOR THIS INVESTIGATION IS ALREADY ARCHIVED IN THE SMALL BODIES NODE OF THE PLANETARY DATA SYSTEM THUS MAKING THIS STUDY APPROPRIATE FOR THE ROSETTA DATA ANALYSIS PROGRAM. THE TEAM INCLUDES INVESTIGATORS AND COLLABORATORS WITH ALL OF THE NECESSARY EXPERTISE INCLUDING ANALYSIS ANALYSIS TOOLS FOR THE DATA IN QUESTION CALIBRATION OF THE DATA AND AN INTIMATE KNOWLEDGE OF ALL THE NECESSARY DETAILS. ANALYSIS TOOLS INCLUDE THE SPHERICAL HARMONICS INVERSION METHOD AND THE AMPS COMET COMA MODEL. TEAM MEMBERS ARE THE EXPERTS IN THE DETAILS OF BOTH THE VIRTIS-M AND VIRTIS-H CHANNELS. WE HAVE EXPERIENCE IN RETRIEVING AND USING OSIRIS IMAGES FROM THE PDS.
$592,903FY2020National Aeronautics and Space AdministrationNASA
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