''Phobos events'': Signatures of solar wind dust interaction

In 1989, during its first three elliptical orbits Mars, the Phobos-2 spacecraft observed significant plasma and magnetic field perturbations near of the orbit of the Martian moon Phobos. They are commanly considered as indirect evidence for the presence of a dust torus along the Phobos orbit, predicted by Sloter (CRSR 462, 1971), but not yet directly. It is the purpose of this paper to test thesis. To this end, the solar wind interaction with a charged dust column is studied on the basis of a Hall-MHD/fully kinetic plasma description, and the results are compared with observations. The events are suggested to be the signatures of crossing of a fast magnetosonic/whistler Mach cone originating from a dust obstacle with a disk-like cross-section. To reproducing typical features of the observed perturbations, a. shift the obstacle centre from the Phobos orbit radially outwards by about 1000 km and a peak charge a density of at least of the order of the solar wind density are required. Copyright (C) 1996 Elsevier Science Ltd