IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2022B020 PROGRAM_TITLE Investigating nitrile chemistry on Titan PROGRAM_INV1 Athena Coustenis PROGRAM_INV2 Therese Encrenaz PROGRAM_INV3 Thomas Greathouse PROGRAM_INV4 Conor Nixon PROGRAM_INV5 Panayotis Lavvas PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG The atmosphere of Titan is known to be a laboratory of complex organic chemistry. From the Voyager and Cassini-Huygens missions, several hydrocarbons and nitriles have been detected and their seasonal variations have been partly monitored. Other minor species have been detected from the ground. These results have been modeled in photochemical models that have also predicted the presence of other minor species, among which some have infrared transitions in the 5-25-micron spectral range where propane and allene have already been detected by TEXES. We propose here to use TEXES to study the HCN and HC3N molecules on Titan and to search for C4H3N and C4H7N, two nitriles which have only been observed with ALMA or not at all respectively. The detection and monitoring of C2H2, HCN and HC3N with TEXES will provide an effective follow-up on the results from the Cassini-Huygens mission, five years after the end of the mission. For the first time, it will be possible to monitor Titan's nitrile species 2.5 years before the northern autumn equinox, and thus to access the atmosphere at a season which was not previously observed from space [as Voyager/IRIS and Cassini/CIRS mostly observed Titan during northern spring and summer] nor, to our knowledge, significantly from the ground. In addition, an extended temporal monitoring of the nitrile minor species by TEXES could be a valuable input to the Dragonfly future mission to Titan currently in development. TEXES is complementary to ALMA which probes different altitude levels and requires a specific spectral setting for each rotational transition. Combining TEXES and ALMA results we will be able to derive vertical profiles since we sound different atmospheric levels thus better constraining the atmospheric chemistry. PROGRAM_ABSTRACT_END