Planetary missions in the Shuttle era

A conservative fifteen-year plan for planetary exploration is presented in which the Space Shuttle is considered as just a basic transportation system that should be quite economical and have excellent reliability. It is noted that these planned missions are limited by the out-of-orbit escape capability of the Shuttle's Interim Upper Stage (IUS), rather than by the orbital payload capability of the Shuttle itself. A mission model is provided in which a rather even balance is maintained among missions to the inner planets, the outer planets, the comets and asteroids, and interplanetary missions out of the ecliptic plane; the cost estimate for this model is plotted. Launch requirements for the various missions are compared with the performance available from various IUS candidates under evaluation, and it is shown that even the lower-performance candidates can be brought up to the capability of the current Titan IIIE/Centaur/TE-364 expendable launch vehicle, which is adequate for most of the missions in the program. Missions which require higher-performance IUS options are noted, including the Mariner Jupiter and Saturn Orbiters.