# # Program information file # PROGRAM_ID 2021A047 PROGRAM_TITLE An experiment to detect the waterborne H3O+ ion in Saturn's atmosphere, with the purpose to constrain the mass loss rate and ultimately age, of Saturn's rings PROGRAM_INV1 James O'Donoghue PROGRAM_INV2 Steve Miller PROGRAM_INV3 Sergey Yurchenko PROGRAM_INV4 Thomas Greathouse PROGRAM_INV5 Luke Moore PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG Charged icy grains are able to stream from the rings into Saturn's atmosphere via the magnetic field. This process, termed 'ring rain', erodes and sculpts the ring system through the interplay between electromagnetic, gravitational and centrifugal forces. The rate of ring mass loss is an essential input to determinating the evolution and lifetime of the rings into the future. This proposal is aimed at directly constraining the mass loss rate of the rings for the first time. A second goal is to elucidate the chemical composition of Saturn's low-latitude-to-equatorial ionosphere. If successful, we will have also proved we can detect the signature, quantity and temperature of water in the outermost layer of a planet - the ionosphere. In the past, only indirect measurements have been used to detect ring mass loss rate to the atmosphere, namely by measuring the depletions of the H3+ molecule. In this proposal however we will attempt, using a new high resolution line list derived largely for the purpose of this very proposal [by Co-I Yurchenko], to detect the waterborne H3O+ ion for the first time in Saturn's atmosphere. This will be used to find the flux of H3O+ into Saturn, thereby shedding light on the ring erosion timescale. We intend to use a 5.5x1.4 arcsecond slit of TEXES at R~85,000 to search for H3O+ lines near 10.5 microns. The slit is to be oriented in an east-west direction and scanned from northern pole to equator in order to build up a longitude/latitude map. We intend to do this over 3 nights of observations in order that the ring mass loss rate to Saturn can be quantified accurately [with higher signal to noise data]. PROGRAM_ABSTRACT_END