XM Status, Priorities and Plans Icy Satellites C. J. Hansen, A. Hendrix January 2008

Observation Types Primary Mission ICYMAP - Map uv albedo at high resolution; scans across satellite ICYEXO - Detect volatiles by absorption; observe occultation of “bright 19” star ICYOCC - Chord for satellite location, size; observe occultation of star ICYLON - Sample uv albedo as f(phase, longitude); Sit ‘n stare ICYSTARE - Detect volatiles as emission feature; long sit ‘n stare integration ICYATM - Detect oxygen in region around Enceladus; mini system scan New ICYECL - Look for post-eclipse brightening as evidence of volatiles condensing during eclipse; sit ‘n stare ICYLIMB (new) - Look for volatiles near limb; slow scan onto limb ICYPLU - long integration to look for Enceladus’ plume (rider on ISS) Notes: Observation types are in priority order. Ok to give up ICYATMs and ICYOCCs. Fight for ICYEXOs. Status: All non-targeted flyby CIMS entries are in, Observation Descriptions have been populated with IEB settings desired

ICYMAP Example Will get maps of Enceladus, Dione, and Rhea in the XM

Enceladus Observation Suite System scans show variable atomic oxygen in Saturn’s system Localized scans across Enceladus give higher resolution picture of the distribution of oxygen Link to highest resolution to characterize the eruptive state Execute routinely to monitor Enceladus’ activity remotely

Enceladus Flyby Timelines

Solar Occultation Rev 131 We will observe an occultation of the sun on Rev 131 New results are in the EUV, which gives us access to a different wavelength range than the FUV The big scientific payoff is the chance to definitively detect / measure nitrogen in the plume - important for models of chemistry-driven dynamics in the interior