Cartographic Mapping of the Icy Satellites Using ISS and VIMS Data

Abstract

The sizes and shapes of six icy Saturnian satellites have been measured from Cassini Imaging Science Subsystem (ISS) data, employing limb coordinates and stereogram-metric control points. Mimas, Enceladus, Tethys, Dione and Rhea are well described by triaxial ellipsoids; Iapetus is best represented by an oblate spheroid. The ISS acquired many high-resolution images (<1 km/pixel) during close flybys of the medium-sized icy Saturnian satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Iapetus, and Phoebe). We combined these images with lower-resolution coverage and a few images taken by Voyager cameras to produce high-resolution mosaics of these satellites. The global mosaics are the baseline for high-resolution atlases. The atlases consist of 15 tiles each for Enceladus, Dione, and Tethys, whereas the Iapetus, Mimas, and Phoebe atlases consist of 3, 1, and 1 tile, respectively. The nomenclature used in these atlases was suggested by the Cassini-ISS team and approved by the International Astronomical Union (IAU). The whole atlases are available to the public through the Imaging Team's website (http://ciclops.org/maps/) and from the Planetary Data System (PDS, http://pds-imaging.jpl.nasa.gov/). Additionally to ISS, the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft detected the chemical and physical surface properties of the Saturnian satellites. Multiple VIMS observations were combined into global VIMS maps representing the VIMS coverage achieved during the nominal Cassini mission. Progressed mapping has been done for the satellites Dione, Rhea, and Enceladus.