Deimos: An Obstacle to the Solar Wind

Science  25 Aug 1995:
Vol. 269, Issue 5227, pp. 1075-1078
DOI: 10.1126/science.269.5227.1075


Two isolated solar wind disturbances about 5 minutes in duration were detected aboard the Russian spacecraft Phobos-2 upon its crossing the wake of the martian moon Deimos about 15,000 kilometers downstream from the moon on 1 February 1989. These plasma and magnetic events are interpreted as the inbound and outbound crossings of a Mach cone that is formed as a result of an effective interaction of the solar wind with Deimos. Possible mechanisms such as remanent magnetization, cometary type interaction caused by heavy ion or charged dust production, and unipolar induction resulting from the finite conductivity of the body are discussed. Although none of the present models is fully satisfactory, neutral gas emission through water loss by Deimos at a rate of about 1023 molecules per second, combined with a charged dust coma, is favored.