After a decade long hiatus in launches beyond Earth orbit, NASA’s planetary exploration program is again moving forward, beginning with the Magellan launch to Venus in May 1989 and the Galileo launch to Jupiter in October 1989. These spacecraft will reach their targets in August 1990 and December 1995, respectively. Both are missions of longstanding priority, Magellan to provide the first global high resolution mapping of the cloud-shrouded Venus surface, Galileo to make comprehensive measurements of the Jovian system in follow-up to the 1979/1980 Voyager flybys.

Beyond these two missions there are other already approved missions: the Mars Observer for launch in 1992, the Comet Rendezvous and Asteroid Flyby CRAF mission (Fig. 1) for launch in 1995, and the Cassini mission (Figs. 2 and 3) to Saturn and its moon Titan for launch in 1996. The very diversity of these five missions and their targets (Venus, the Jovian system, Mars, comet Kopff, asteroids Gaspra and Ida by Galileo, Hamburga by CRAF, and Maja by Cassini, and the Saturnian system, is indicative of the strategy being pursued in the program: one of deliberate breadth that seeks to explore all three main classes of solar system bodies (the terrestrial planets, the outer giants and their moons, and the primitive small bodies).