# # Program information file # PROGRAM_ID 2021B107 PROGRAM_TITLE Bridging the 'Rosetta Stone' of Cometary Science: A Multi-Wavelength, Multi-Epoch Campaign Toward Comet 67P/Churyumov-Gerasimenko During its First Apparition Since the Conclusion of the Rosetta Mission PROGRAM_INV1 Nathan Roth PROGRAM_INV2 Chemeda Ejeta PROGRAM_INV3 Boncho Bonev PROGRAM_INV4 Neil Dello Russo PROGRAM_INV5 Michael DiSanti PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG We propose to use iSHELL to measure the composition of parent volatiles in comet 67P/Churyumov-Gerasimenko [hereafter 67P] during its first perihelion passage following the conclusion of the Rosetta mission. Maximizing the science returns of such missions requires placing their in-situ results into the context of the diverse comet population as revealed by ground-based IR studies. We will measure [or stringently constrain] the production rates of H2O, C2H6, CH3OH, H2CO, HCN, and C2H2 during four epochs spread across two months. We will bridge the results delivered by the ``Rosetta Stone'' of cometary science with remote sensing measurements of the broader population by addressing five tasks during 67P's highly favorable 2020 apparition. We will [1] Compare global ground-based measurements against bulk abundances derived from Rosetta. This will provide the missing link between two major databases: remote sensing of many comets and the expansive Rosetta results for 67P. [2] Test potential pre-/post-perihelion asymmetries. We will test the dramatic evolution in coma outgassing measured by Rosetta as 67P approached and passed through perihelion. [3] Resolve Rosetta discrepancies in the CH3OH abundance. CH3OH provides insights into coma chemistry and thermal physics from the near-IR to the radio, and clarifying its abundance in 67P is critical to resolving the discrepancy in CH3OH/H2O reported by ROSINA and MIRO. [4] Determine coma spatial relationships. We will test the Rosetta results suggesting distinct outgassing sources for polar vs. apolar ices; and [5] Measure HDO/H2O through contemporaneous IRTF/ALMA measurements. We will provide H2O measurements [ALMA can measure HDO but not H2O in 67P] in order to test the high D/H ratio in H2O reported by Rosetta. This multi-wavelength campaign will test the Rosetta results from a global perspective during the most favorable apparition of 67P until 2034. PROGRAM_ABSTRACT_END