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THE GOAL OF THIS PROPOSAL IS TO DETERMINE THE RELIABILITY OF A SINGLE DEUTERIUM TO HYDROGEN RATIO (D/H) MEASUREMENT IN THE COMA OF A COMET. D/H IN COMETARY WATER IS A CRITICAL TOOL FOR EVALUATING THE ORIGIN OF WATER ON EARTH AND OTHER SOLAR SYSTEM BODIES. POTENTIAL VARIATIONS WITH TIME OR SPATIALLY WITHIN THE COMA COULD HAVE A SIGNIFICANT IMPACT ON STUDIES OF THE ORIGIN AND EVOLUTION OF THE SOLAR SYSTEM. RECENT OBSERVATIONS OF COMET C/2014 Q2 (LOVEJOY) SHOW A FACTOR OF ~2 DIFFERENCE BETWEEN D/H MEASURED BEFORE AND AFTER PERIHELION. THESE DIFFERENCES COULD BE DUE TO OBSERVATION METHODS OR THEY COULD INDICATE A CHANGE IN D/H. IF D/H DID CHANGE THE VARIABILITY OBSERVED AMONG COMETS MAY BE PARTIALLY RELATED TO PROCESSES ON THE NUCLEUS AND IN THE COMA. ACCORDING TO PAGANINI ET AL. (2017): A PROPER ASSESSMENT OF POSSIBLE EVOLUTIONARY EFFECTS ON THE D/H RATIO IN A COMET WOULD REQUIRE CADENCED ASTRONOMICAL OBSERVATIONS USING THE SAME FACILITY/TECHNIQUE TO AVOID POSSIBLE SYSTEMATICS. WE DEMONSTRATE HERE THAT STATISTICALLY SIGNIFICANT VARIATION IN THE D/H WAS OBSERVED WITH THE ROSETTA ORBITER SPECTROMETER FOR ION AND NEUTRAL ANALYSIS (ROSINA) DOUBLE FOCUSING MASS SPECTROMETER (DFMS) ESTABLISHING THAT THIS IS THE IDEAL DATASET TO PROVIDE THE ASSESSMENT RECOMMENDED BY P17. IN ORDER TO ACHIEVE OUR GOAL WE WILL ANSWER FOUR SCIENCE QUESTIONS: 1. DO SUBLIMATION PROCESSES AFFECT THE D/H OBSERVED IN A COMA? 2. DOES DUST ON THE COMET SURFACE INFLUENCE THE D/H IN WATER OBSERVED IN A COMA? 3. DO ENERGETIC IONS INFLUENCE THE D/H ON SHORT TIME SCALES? 4. WHAT LEVEL OF UNCERTAINTY EXISTS FOR A SINGLE D/H MEASUREMENT FOR A COMET? THE PROPOSED WORK IS DIRECTLY RELEVANT TO THE NASA RDAP PROGRAM BECAUSE THE RESULTS WILL ENHANCE THE SCIENTIFIC RETURN OF THE ROSETTA MISSION. FURTHERMORE ALTHOUGH THE PI HAS EXTENSIVE EXPERIENCE WITH ISOTOPIC STUDIES SHE HAS NEVER BEEN FUNDED TO WORK WITH THE ROSINA DFMS DATA. THEREFORE THIS PROPOSAL WILL BROADEN THE SCIENTIFIC PARTICIPATION IN THE ANALYSIS OF ARCHIVED DATA COLLECTED FROM THE ROSETTA AND PHILAE SPACECRAFT.

$406,410FY2020National Aeronautics and Space AdministrationNASA

The Johns Hopkins University

Investigators

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THE GOAL OF THIS PROPOSAL IS TO DETERMINE THE RELIABILITY OF A SINGLE DEUTERIUM TO HYDROGEN RATIO (D/H) MEASUREMENT IN THE COMA OF A COMET. D/H IN COMETARY WATER IS A CRITICAL TOOL FOR EVALUATING THE ORIGIN OF WATER ON EARTH AND OTHER SOLAR SYSTEM BODIES. POTENTIAL VARIATIONS WITH TIME OR SPATIALLY WITHIN THE COMA COULD HAVE A SIGNIFICANT IMPACT ON STUDIES OF THE ORIGIN AND EVOLUTION OF THE SOLAR SYSTEM. RECENT OBSERVATIONS OF COMET C/2014 Q2 (LOVEJOY) SHOW A FACTOR OF ~2 DIFFERENCE BETWEEN D/H MEASURED BEFORE AND AFTER PERIHELION. THESE DIFFERENCES COULD BE DUE TO OBSERVATION METHODS OR THEY COULD INDICATE A CHANGE IN D/H. IF D/H DID CHANGE THE VARIABILITY OBSERVED AMONG COMETS MAY BE PARTIALLY RELATED TO PROCESSES ON THE NUCLEUS AND IN THE COMA. ACCORDING TO PAGANINI ET AL. (2017): A PROPER ASSESSMENT OF POSSIBLE EVOLUTIONARY EFFECTS ON THE D/H RATIO IN A COMET WOULD REQUIRE CADENCED ASTRONOMICAL OBSERVATIONS USING THE SAME FACILITY/TECHNIQUE TO AVOID POSSIBLE SYSTEMATICS. WE DEMONSTRATE HERE THAT STATISTICALLY SIGNIFICANT VARIATION IN THE D/H WAS OBSERVED WITH THE ROSETTA ORBITER SPECTROMETER FOR ION AND NEUTRAL ANALYSIS (ROSINA) DOUBLE FOCUSING MASS SPECTROMETER (DFMS) ESTABLISHING THAT THIS IS THE IDEAL DATASET TO PROVIDE THE ASSESSMENT RECOMMENDED BY P17. IN ORDER TO ACHIEVE OUR GOAL WE WILL ANSWER FOUR SCIENCE QUESTIONS: 1. DO SUBLIMATION PROCESSES AFFECT THE D/H OBSERVED IN A COMA? 2. DOES DUST ON THE COMET SURFACE INFLUENCE THE D/H IN WATER OBSERVED IN A COMA? 3. DO ENERGETIC IONS INFLUENCE THE D/H ON SHORT TIME SCALES? 4. WHAT LEVEL OF UNCERTAINTY EXISTS FOR A SINGLE D/H MEASUREMENT FOR A COMET? THE PROPOSED WORK IS DIRECTLY RELEVANT TO THE NASA RDAP PROGRAM BECAUSE THE RESULTS WILL ENHANCE THE SCIENTIFIC RETURN OF THE ROSETTA MISSION. FURTHERMORE ALTHOUGH THE PI HAS EXTENSIVE EXPERIENCE WITH ISOTOPIC STUDIES SHE HAS NEVER BEEN FUNDED TO WORK WITH THE ROSINA DFMS DATA. THEREFORE THIS PROPOSAL WILL BROADEN THE SCIENTIFIC PARTICIPATION IN THE ANALYSIS OF ARCHIVED DATA COLLECTED FROM THE ROSETTA AND PHILAE SPACECRAFT. · GrantIndex