Two early missions to the comets.

Early missions to the comets Grigg-Skjellerup in 1977 and Encke in 1980 are suggested as precursors to more ambitious missions to Encke rendezvous in 1984 and Halley intercept in 1986. The spacecraft structures, power systems, telemetry, configurations, and launch vehicles considered appropriate for these two missions are actual equipments ready for applications. The mission objectives would be exploration of the nature of the solar wind interaction with comets, the composition of the gaseous cometary atmosphere, and possibly the details of the trailing portion of a comet (ion and dust tails).