Cassini-Huygens (U.S., the European Space Agency, and the Italian Space Agency)

Destination: Saturn. Launched: Oct. 15, 1997. Arrival: July 1, 2004. Mission: To orbit Saturn for four years. The Cassini-Huygens mission is named for the Italian-French astronomer Jean Dominique Cassini, who discovered four of Saturn's major moons, and the Dutch scientist Christiaan Huygens, the first to find Saturn's rings and its largest moon, Titan. Cassini-Huygens encountered Jupiter on Dec. 30, 2000, and flew down the giant planet's magnetotail (the elongated tail of a planet's magnetic field facing away from the Sun), performing studies complementing the Galileo mission until March 31, 2001. On July 1, 2004, Cassini reached Saturn's rings and went into the first of 74 orbits of the planet and began sending back images of the rings and the moons. On Dec. 24, 2004, the Huygens probe separated from the Cassini spacecraft and in Jan. 2005 descended to Titan, transmitting information for its 21/2 hour descent and then for more than 90 minutes on the moon’s surface. The Cassini craft is slated to continue its mission until July 1, 2008.

Mars Global Surveyor (MGS) (U.S.) 2001 Mars Odyssey (U.S.)