82-8 Continued Exploration of Surface Changes at Enceladus During the Cassini Mission

Session: Friends of Hoth, Episode IX: The Rise of Icy Ocean Worlds

Presenting Author:

Leah Sacks

Authors:

Sacks, Leah E¹, Patthoff, Alex², Bland, Mike³, Phillips, Cynthia B⁴, Hoppa, Greg⁵, Neish, Catherine⁶, Leonard, Erin J.⁷

(1) NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, (2) Planetary Science Institute, La Habra Heights, CA, USA, (3) USGS Astrogeology Science Center, Flagstaff, AZ, USA, (4) NASA, Jet Propulsion Agency, California Institute of Technology, Pasadena, CA, USA, (5) Raytheon, Hampstead, NH, USA, (6) The University of Western Ontario, Department of Earth Sciences, London, ON, Canada; Planetary Science Institute, Tucson, AZ, USA, (7) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA,

Abstract:

NASA’s Cassini and Voyager missions showed the surface of Saturn’s moon Enceladus to be geologically complex and likely relatively young. The icy moon has a unique combination of substantially cratered surfaces and heavily tectonically modified areas. The tectonized terrains are relatively devoid of craters which suggests that the crust has been resurfaced or reworked comparatively recently. The presence of water-ice plumes at the south pole of Enceladus confirms active geological processes on the moon. The Cassini mission spanned ~13 years (2004-2017), capturing repeat images of the surface of Enceladus at many points during that time. By examining these images, we can learn about the evolution of Enceladus and its active processes. 

Previous results from this project noted a disappearing Dark Spot (~ 1 km in diameter) on the moon’s surface. We suggest the Dark Spot was likely being covered over by plume deposits and E-ring material. While the Dark Spot has not been conclusively tied to a particular formation mechanism, its morphology has been likened to that of an impact ejecta blanket. The disappearing Dark Spot indicates active deposition on the surface of Enceladus and highlights the possibility that previous similar albedo features have been covered over time. 

Current efforts on this project focus on two additional areas of potential activity on Enceladus, non-synchronous rotation (NSR) and changes at the southern pole. By comparing the relative location of the terminator in Voyager and Cassini images to their predicted location based on the current rotation model, we have constrained the period of any NSR to be ≥ 10⁴ years. Work is ongoing to improve these measurements. At the south pole, our search for changes has focused on the area near the Tiger Stripes, large fissures from which the plumes emanate. However, our work exploring this region has not found any detectable geological changes in the Cassini data, the only mission to directly image the south pole. 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11062

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