# # Program information file # PROGRAM_ID 2022B019 PROGRAM_TITLE Probing the sources and sinks of HCl on Mars PROGRAM_INV1 Sara Faggi PROGRAM_INV2 Shohei Aoki PROGRAM_INV3 Giuliano Liuzzi PROGRAM_INV4 Hideo Sagawa PROGRAM_INV5 Geronimo Villanueva PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG Recently, a small amount of hydrogen chloride [HCl] was discovered in the Mars atmosphere. HCl is the first confirmation of any chlorine species in the Mars atmosphere. An active Cl cycle, including a possible interaction between surface and atmosphere, is proposed, however, the mechanisms to produce and destroy HCl in the atmosphere is still unknown. To provide a new insight into this issue, we propose to observe temporal evolution of HCl and water vapor global maps across the southern summer period, when the abundance of HCl is known to suddenly increase, in order to capture how HCl is released, spread, depleted, and disappeared. In 2022B the Martian seasons range from Ls ~ 277degrees in early August 2022 to Ls ~ 17degrees at the end of January 2023, making this semester critical for HCl investigations, since its peak is expected to be between Ls ~ 270degrees and 320degrees. iSHELL spectral setting Lp1 will be adopted. Custom setting covers from 3.71 to 3.32 um, providing simultaneous measurements of H2O, HDO, CO2, HCl, their isotopic signatures and several other trace gases. To map the planet, we will set the iSHELL slit [15''x0.375''] in the planet North-South direction and we will scan across the East-West direction with a step size of ~ 1', with a total number of positions depending on the angular diameter of Mars. PROGRAM_ABSTRACT_END