Abstract
Titan was a mostly unknown world prior to the Cassini spacecraft’s arrival in July 2004. We
review the major scientific advances made by Cassini’s Titan Radar Mapper (RADAR) during
13 years of Cassini’s exploration of Saturn and its moons. RADAR measurements revealed
Titan’s surface geology, observed lakes and seas of mostly liquid methane in the polar regions,
measured the depth of several lakes and seas, detected temporal changes on its surface, and
provided key evidence that Titan contains an interior ocean. As a result of the Cassini mission,
Titan has gone from an uncharted world to one that can be considered as the Earth of the outer
solar system, exhibiting a variety of Earth-like geologic processes and surface-atmosphere
interactions. Titan has also joined the ranks of “ocean worlds” along with Enceladus and Europa,
which are prime locations for astrobiological research.