# # Program information file # PROGRAM_ID 2024B080 PROGRAM_TITLE Characterizing Organic and Dust Properties in Comets PROGRAM_INV1 Bin Yang PROGRAM_INV2 Aigen Li PROGRAM_INV3 Michael Kelley PROGRAM_INV4 Ruining Zhao PROGRAM_INV5 PROGRAM_SCICAT comets PROGRAM_ABSTRACT_BEG Comets represent some of the least thermally altered and most pristine material available today. The particle size distribution and composition of cometary dust contain crucial information about the chemical and physical processes in the early solar system. The presence of polycyclic aromatic hydrocarbon [PAH] molecules, commonly found in the interstellar medium [ISM] of our galaxy and beyond, is anticipated but rarely detected in comets. Observing and characterizing PAHs in comets creates a unique bridge between the ISM and cometary environments. However, studying PAHs and dust properties in comets is limited to longer wavelengths beyond 2.5 micron, which is very challenging for ground-based observations. Our knowledge of these materials is thus highly limited. In 2024B, one dynamically new Oort Cloud comet, C/2023 A3, is expected to reach an exceptional brightness during its perihelion passage in late September. If A3 reaches the predicted brightness, it would offer a great opportunity to conduct a comprehensive study of PAHs and dust in comets in the 3-micron region and the thermal infrared. We propose to observe this bright comet using SpeX in the L-band and MIRSI in the mid-infrared. PROGRAM_ABSTRACT_END