The Cassini-Huygens mission is a multibillion dollar, international scientific collaboration to study Saturn and its environment—in particular, Saturn’s largest moon, Titan. NASA, ESA (the European Space Agency), and ASI (the Italian Space Agency) collaborated on this powerfully equipped exploration mission, which consisted of the Cassini orbiter that also carried and supported the Huygens lander mission to Titan. Along the way, Cassini also flew by Jupiter. With budget constraints and philosophical changes in the world’s space agencies, Cassini-Huygens is probably the largest and most expensive planetary exploration mission for the foreseeable future.