# # Program information file # PROGRAM_ID 2024A072 PROGRAM_TITLE Characterizing Organic Matter 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 Dust plays an important role in the early stages of planet formation. Characterizing cometary dust therefore provides valuable insights into the formation of planetary systems 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 PAH 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 thus remains limited. In 2024A, two comets, 12P and C/2021 S3, are expected to be exceptionally bright during their perihelion passages. If they do reach the predicted brightness, it would offer a great opportunity to conduct a comprehensive study of PAHs and dust in comets beyond 2.5 micron. We propose to observe these two comets in the L-band with SpeX and in the mid-infrared using MERSI. PROGRAM_ABSTRACT_END