(Proposal ID) S17A-100 (PI) Kawakita, Hideyo (Proposal Title) Hypervolatiles in comet 45P/HMP: Probing formation chemistry vs. evolution (Abstract) We propose to use NIRSPEC at Keck II to measure the chemical composition of comet 45P/Honda-Mrkos-Pajdusakova (hereafter 45P/HMP), a short-period Jupiter- family comet (JFC) of probable Kuiper belt origin. Determining the composition and structure of cometary nuclei is essential to understanding the formation and evolution of volatile material within our solar system. We will determine the chemical composition in this comet through a sensitive search for the following molecular species: H_2O, CO, CH_4, CH_3OH, H_2CO, C_2H_6, HCN, C_2H_2, NH_3, and NH_2. Hypervolatiles such as CH_4 and CO (sublimation temperatures 31 and 24 K) are the most sensitive to thermal processing history, so their quantification in comets (JFCs in particular) is critical; however, their detection requires both sufficient comet brightness and adequate geocentric Doppler shift to avoid extinction of comet lines from terrestrial counterparts. Semester 2017A provides a rare opportunity to determine the chemical composition of hypervolatiles in a JFC, 45P/HMP. The comet will be available for enough time and is sufficiently productive to detect spectral lines when comet geocentric velocities large enough (> 15 km/s) to shift cometary CO and CH_4 lines from telluric counterparts.