0 Assigned ID: 3280 ----- Attempting Submission 1 (Fri Mar 25 15:39:20 GMT 2022) ----- HST Phase I Proposal 3280 successfully submitted. Receipt: # 3280-1 ----- Attempting Submission 2 (Fri Mar 25 18:55:34 GMT 2022) ----- A current major problem in astrophysics is the depletion of sulfur in molecular clouds, protostellar cores, and protoplanetary disks relative to cosmic abundances. In contrast, comets appear to have atomic sulfur abundances that are larger than expected given the observed sulfur-bearing parent molecules. Mapping the sulfur chemistry of comets and characterizing trends between the two dynamical classes, isotropic and Jupiter family comets, are essentially to our understanding of astrophysical sulfur chemistry. We request Legacy Archival Research funding over three years to determine for the first time the elemental abundance and sulfur chemistry of the entire UV sample of 1514 observations of 78 comets, obtained in 104 programs by the Hubble Space Telescope and International Ultraviolet Explorer, obtained from the Mikulski Archive for Space Telescopes. To execute this program, we will 1) recalibrate, re-extract, and re-reduce UV cometary spectra containing atomic sulfur and sulfur-bearing molecular emissions; 2) interpret the observed emission intensities with Monte Carlo distribution and radiative transfer models; and 3) report the the derived column densities, production rates, and relative abundances of atomic sulfur and relevant sulfur-bearing molecules. This exhaustive re-calibration and re-analysis of the UV comet dataset will fundamentally change our understanding of cometary atomic sulfur abundances and parent molecules and provide critical information to the larger astrophysical question about sulfur's hiding place in molecular clouds, protostellar cores, and protoplanetary disks. Our team has extensive experience with HST and consists of expert observers, modelers, and data analysts, who have developed sophisticated techniques for measuring and interpreting comet activity and composition. All team members will aid in integrating the results from the IUE, HST FOS, COS, and STIS data and will be involved in the preparation of scientific publications. The PI and team leader John Noonan (Auburn U.) is a visiting research scholar with Far Ultraviolet (FUV) comet observation experience with both Rosetta Alice UVS and HST, and is an expert in the analysis and interpretation of cometary spectra. Dennis Bodewits (Auburn U.) is an expert on comet activity and coma physics and brings experience with the Rosetta and EPOXI comet missions. He has led several comet observing campaigns for space-based telescopes, including comet observations with HST, Chandra, XMM-Newton, and the Neil Gehrels-Swift Observatory. Kathy Mandt (JHU/APL) is an expert in cometary plasma physics and in connecting comet composition to the origin of volatiles in solar system atmospheres. She is a team member of the Rosetta Plasma Consortium instrument team and funded by NASA to conduct analysis of Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) data. Lori Feaga (UMD) is an expert on cometary activity in the UV, visible, and NIR wavelengths of light. She has been a Co-I on the Rosetta Alice UVS, been involved with the Deep Impact and EPOXI missions, and has used HST and IUE instrumentation extensively to characterize the sulfur emissions of the Jovian satellites. Mohi Saki (Auburn U.) is an expert in the long slit near-IR spectroscopic measurements of comets. He has led multiple near-IR observations using iSHELL spectrograph at NASA Infrared Telescope Facility (IRTF) and is an expert on sulfur-bearing molecule chemistry. Steven Bromley (Auburn U.) is an expert in spectral modeling of ultraviolet/visible emission in laboratory and cometary plasmas. He has developed Python-based codes for computing fluorescence efficiencies and benchmarked them against archived high-resolution spectra. Joel Parker (SwRI) is the PI for the Rosetta Alice UVS and is an expert in the analysis of cometary FUV observations. Additionally, Parker has observed with IUE and used IUE archive data for decades, and created the IUE Atlas of B-Type Spectra (Parker et al. 1995). Our team's background and recent successful campaigns to characterize the UV atomic and molecular abundances of interstellar comet 2I/Borisov (GO-16049), comet 46P/Wirtanen (GO-15625), and 67P/Churyumov-Gerasimenko(GO-16770) place us in a unique position to similarly assess the complex sulfur diagnostics available in the rich catalog of UV comet observations. Solar System Astronomy 0 Legacy false false true false false false SUPPORTED