Halley's Comet – Its Secrets Revealed

Abstract

For several reasons Halley's Comet is the most important among the 750 known comets, and it comes therefore as no surprise that not only one but six spacecraft from four space agencies were sent to this comet and that ground-based astronomers mounted one of the largest observational campaigns ever on an astronomical object. With its 76-year period, Halley's Comet is truly a once-in-a-Iifetime opportunity. The six encounters with Halley's Comet occurred in March 1986 and were all highly successful. The suite of experiments on these fly-by spacecraft revealed the composition of the neutral gas, ions and dust in the coma, observed the complex plasma physical processes resulting from the interaction between the solar wind and the cometary ionosphere and, most important of all, detected and imaged the cometary nucleus for the first time.