Relevant Coma Composition Investigations for the Comet Interceptor Mission

The Comet Interceptor Mission (ESA/JAXA) plans to visit a yet-to-be-discovered long-period comet or interstellar object by waiting for up to several years at Earth’s L2 Lagrange Point for a target of opportunity. Its primary science goal is to characterize the object’s surface composition, shape and structure, and the composition of its gas coma. The mission consists of up to three spacecraft, the primary A (ESA) and two accompanying ones, B1 (JAXA) and B2 (ESA). In this presentation, we focus on the unique synergetic activities of two mass spectrometers, a neutral mass spectrometer (MANIaC) on A and the Plasma Suite (PS) on B1, to investigate the chemical composition of the coma. Both can be operated in a complementary fashion, MANIaC at a further cometocentric distance than PS, at different locations and at the same time to sort out spatial from temporal effects. Relevant investigations of the coma composition and chemistry within the technical specifications of the instruments could address several unsolved questions, such as, 1) the relationship between ammonium salts (including NH₄⁺) and the nitrogen inventory of cometary volatiles as well as their isotopic composition; 2) likely parents of phosphorous and its inner coma chemistry; 3) the nature of neutral sodium in the coma and tails, and its relationship to gas-phase species and refractory dust particles, and 4) the source and chemistry of hydrogen halides, HCl and HF. The Comet Interceptor Mission is posed to be an important mission for advancing our knowledge of comets, especially clues for understanding coma chemistry and composition.