Collaborative Proposal: Comets and the History of Volatile Matter During Planetary System Formation

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Comets are early Solar System objects, mostly unchanged from the time the Solar System was created. The orbits of comets trace them to the locations in the outer Solar System where they formed. The compositions of molecules released from a comet can be measured by looking at their spectral signals. Combining these compositions with the comet orbits allows scientists to learn what materials were present at different locations in the early Solar System. The investigators will measure the amounts of many molecules in comet spectra, including H2O, HDO, CH4, C2H2, C2H6, H2S, SO2, OCS, CO, H2CO, CH3OH, HCOOH, HCN, HNC, CH3CN, HC3N, NH2CHO, and NH3. They will use ground-based observatories such as the NASA Infrared Telescope Facility, the W. M. Keck Observatory, and the Atacama Large Millimeter/submillimeter Array. The years of 2017-2019 provide an excellent opportunity to study Jupiter Family Comets - comets with smaller orbits for which little is known about their compositions. This research serves the national interest by advancing our knowledge of the materials that served as the building blocks of our Solar System. Shows at the Watson-King Planetarium, Towson University, and the University of Missouri, Saint Louis' new planetarium will feature this research. Students from St. Louis and Baltimore, including many minority students, will have the chance to see them. The Principal Investigators will use high-resolution molecular spectroscopy of comets to measure the compositions of volatiles released from their nuclei, and to test theories about the early formation of the Solar System. While the orbits of observed comets link them to their dynamical reservoir (the distant Oort cloud or closer Kuiper belt), the suite of detected molecules for an individual comet provides a "snapshot" of the volatile inventory at their location in the protoplanetary disk where these comets formed. The investigators will use ground-based near-infrared and radio observatories, including the NASA Infrared Telescope Facility, the W. M. Keck Observatory, and the Atacama Large Millimeter/submillimeter Array. By combining the advantages of each wavelength domain, the investigators' goal is to measure the relative abundances among various molecular species, including H2O, HDO, CH4, C2H2, C2H6, H2S, SO2, OCS, CO, H2CO, CH3OH, HCOOH, HCN, HNC, CH3CN, HC3N, NH2CHO, and NH3. New observations are planned of Jupiter Family comets and Oort cloud comets. The 2017-2019 period brings the best opportunity for many years to study Jupiter Family comets - a dynamical class underrepresented in compositional studies of all parent volatiles. These studies will be integrated into a planetarium program that will be hosted at the Watson-King Planetarium, Towson University, and at the University of Missouri, Saint Louis' new digital planetarium, reaching St. Louis and Baltimore students, including many underrepresented minorities. One investigator will also mentor graduate and undergraduate students.