Following Iapetus’s Steps: An Analysis of Organic Materials on Rhea

The Cassini Mission observed Saturn’s icy satellite, Rhea, using the Visible and Infrared Mapping Spectrometer (VIMS). Previous research has utilized VIMS to examine other icy satellites such as Iapetus, Hyperion, and Phoebe with the goal of analyzing their spectral signature and to extract and characterize that of the dark material(s) present on their surfaces. Continuing this research for Rhea, we extract and measure the aliphatic and aromatic bands at 3.41 and 3.28 um, respectively. These bands have been proven to be the best candidates for the task. This continued investigation of Saturn’s icy satellites provides a comparison among potentially distinct organic materials. Our analysis follows similar techniques seen in “Infrared spectroscopic characterization of the low-albedo materials on Iapetus” by Dalle Ore et al. (2012) and “Aromatic and aliphatic organic materials on Iapetus: Analysis of Cassini VIMS data” by Cruikshank et al. (2014). We began our analysis by replicating the extraction and investigation done on Iapetus’ organic material. We utilize a clustering technique in which similar materials are grouped together from the spectroscopic standpoint. This data provides important information about the presence of organics (aliphatic and aromatic) on Rhea. However, in conjunction with past analysis of other icy satellites, this also allows us to investigate the connection between the organic material(s) in different parts of the Saturn System. Our findings introduce new information to help answer the question of whether this material is native to its respective satellite or if it’s exogenous in origin.

CMDO, REM, and FS acknowledge support from NASA grant 80NSSC19K1068 and MCG acknowledges support from the SETI Institute REU program (NSF award #2051007, with supplemental funding from the Moore Foundation).