SEARCHING FOR CHANGES AT ENCELADUS: WHAT WE CAN LEARN FROM NOTHING

Saturn’s small (diameter ~500 km) icy moon, Enceladus is one of the most dynamic bodies in the Solar System with large regions on the surface that appear to be relatively young. Active venting of water has been observed in the form of a plume emanating from the south polar region. Numerous large ridges and fissures can be mapped across much of its surface. These features are visible in images provided by two missions that have visited the Saturnian System: Voyager and Cassini. Only the Voyager 2 mission in 1981 obtained images of sufficient resolution for this study. The Cassini mission toured the system from 2004 until 2017 and was able to provide global imaging coverage for Enceladus at scales < 500 m/pixel. For our work, we explore if any observable geological changes occurred on the surface between the visits by Voyager and Cassini or over the course of the Cassini Mission. In the preliminary work presented here, we have begun our search for new craters, new fractures, or the lengthening of existing fractures by comparing Voyager to Cassini images of the trailing hemisphere (a ~35-year timespan). We have also compared Cassini images of the same areas but taken ~1 to 8 a few years apart. Thus far we have not detected any observable changes; however, even if no changes are detected, we will be able to constrain the rates of geological resurfacing at Enceladus.