Science objectives and the Mariner Jupiter/Saturn 1977 mission design

The two Mariner spacecraft to be launched in 1977 to fly by Jupiter and Saturn require a mission design which is heavily dependent on science objectives. These science objectives translate into trajectory requirements imposed by one or more of the eleven instruments aboard Mariner such as distance of closest approach, inclination, occultation, lighting, etc., at the bodies of interest. Also, Jupiter and Saturn cannot be considered as individual targets but as miniature solar systems, where the mission design must apply to the Jovian and Saturnian satellites, and to Saturn's rings. The major objective of this analysis is to translate the science desires into the mission possibilities. Each object, be it a Galilean satellite, Titan, or the ring of Saturn, provides a unique region suitable for scientific investigation for the on-board instruments. Some of these trajectory regions overlap, others do not. Thus, critical choices must be made in selecting the trajectories to be flown by the two Mariner spacecraft. Such a choice, though preliminary, has been made by the Mariner Jupiter/Saturn 1977 (MJS'77) science teams, and a brief discussion of the selection process and the pair of trajectories chosen is presented in this paper.