This paper considers science aspects of a 1980 spacecraft reconnaissance of Comet Encke. The mission discussed is a ballistic flyby (more exactly, a fly-through) of P/Encke, using either a spin-stabilized spacecraft, without despin of instruments, or a 3-axis-stabilized spacecraft. Celestial mechanics and imaging aspects of such a mission have been considered in more detail by Bender (1) and by Jaffe et al (2), respectively. Engineering designs (3, 4) and more detailed accounts of science aspects are given in other documents. A different approach to an Encke ballistic flyby has been suggested by Farquahar et al (5). Yeomans (6) has considered ephemeris uncertainties associated with such missions.