Evidence for near-surface breezes on Comet P/Halley

Abstract

Halley Multicolor Camera (HMC) images taken of the nucleus of Comet P/Halley and its environment from on board ESA's spacecraft, Giotto, provide substantial evidence for flow of dust particles almost parallel to the surface at small cometocentric distances. This evidence is summarized and discussed with reference to other spacecraft experiments, ground-based observations, and current hydrodynamic models of dusty gas jets from comets. It is concluded that lateral transport of material from the active regions on the dayside to the nightside by near-surface gas flow strongly increases the dust density in the anti-sunward direction.