# # Program information file # PROGRAM_ID 2023B057 PROGRAM_TITLE Measuring the Chemical Composition of Jupiter-family Comets 62P/Tsuchinshan and 144P/Kushida PROGRAM_INV1 Younas Khan PROGRAM_INV2 Erika Gibb PROGRAM_INV3 Neil Dello Russo PROGRAM_INV4 Michael DiSanti PROGRAM_INV5 Boncho Bonev PROGRAM_SCICAT comets PROGRAM_ABSTRACT_BEG We propose to use iSHELL to measure the primary volatile composition of Jupiter-family Comets [JFCs] 62/Tsuchinshan and 144P/Kushida. Near-IR observations of JFCs are required in order to better understand their overall chemical composition; however, this important dynamical class of comets is underrepresented in the compositional studies of all primary volatiles sampled in the near-IR to date. The favorable observing conditions afforded by the 2023B apparitions of both 62P/Tsuchinshan and 144P/Kushida provide an excellent opportunity to measure a large set of primary volatiles, including H2O, HCN, C2H2, NH3, CH3OH, H2CO, C2H6, and OCS. Because the short-period JFCs and the long-period Oort Cloud Comets likely formed in overlapping regions of the protosolar nebula, these measurements will help in understanding any systematic differences between the compositional range in the two dynamical classes, which will in turn enhance our understanding of the formation regions and/or any post-formation thermal processing effects in comets. These measurements are also important for developing a taxonomy of comets based on the composition of their primary volatiles obtained using near-IR spectroscopy. During the 2023B apparitions, we will obtain production rates [molecules s-1] and mixing ratios [production rates with respect to H2O] or stringent upper limit of the targeted volatiles in comets 62/Tsuchinshan and 144P/Kushida. Using multiple observations of each comet, we will also analyze any short-term variability and asymmetry about perihelion in the composition of their primary volatiles. Owing to the long-slit capability of iSHELL, we will analyze the spatial outgassing behavior of multiple primary volatiles [especially, H2O, HCN, CH3OH, and C2H6] to understand their outgassing sources and any nucleus associations among them. PROGRAM_ABSTRACT_END