We propose to use NIRSPEC at Keck II to characterize comet 103P/Hartley 2 during its 2023 apparition to investigate the secular variation of cometary activity and chemistry (e.g., depletion in volatile species) in the comet. During its 2010 apparition, this comet was characterized to an unprecedented level through both remote observations (from ground-based observatories and space telescopes) and in situ observations from the EPOXI spacecraft. The 2023 apparition of comet Hartley 2 is two perihelion passages later and is the first favorable ground-based observing opportunity since 2010. Studying parent (originally stored as ices in comet nuclei) volatiles in comets over multiple apparitions is a new frontier in planetary science, and this apparition of Hartley 2 provides an exceptional opportunity to advance our understanding of how chemistry and activity of comets evolve. Our scientific goals are to test (i) secular variation in water gas production near its perihelion passage and (ii) determine if other volatile species are depleted with respect to H2O compared to previous apparitions due to their selective loss as the comet surface has evolved. A third goal (iii) is to determine the spatial distributions of volatiles in the coma to reveal any changes in volatile outgassing behavior since 2010.
This document was translated from LATEX by HEVEA.