Saturns Moon Tethys from Cassini . ... Credit Copyright: Cassini Imaging Team , SSI , JPL , ESA , NASA Explanation: Tethys is one of the larger and closer moons of Saturn. The Cassini spacecraft now orbiting Saturn passed near the frozen moon at the end of October, capturing the most detailed images since the Voyager spacecrafts in the early 1980s. Tethys is composed almost completely of water ice and shows a large impact crater that nearly circles the planet. ... NASA Official: Jay Norris. ...