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Phobos events as precursors of solar wind‐Dust interaction
Author(s) -
Sauer Konrad,
Baumgärtel Klaus,
Motschmann Uwe
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl00236
Subject(s) - physics , solar wind , spacecraft , orbit (dynamics) , mars exploration program , magnetic field , standing wave , astronomy , optics , aerospace engineering , quantum mechanics , engineering
Significant magnetic field perturbations in the solar wind were observed during the Phobos‐2 elliptical orbits around Mars when the spacecraft crossed the Phobos orbit. As remarkable feature, these so‐called Phobos events were detected in all cases only on the upstream side of the Phobos orbit. A simple one‐dimensional fluid model is developed which shows that a thin charged dust cloud with an extension of no more than 100 km is able to produce phase‐standing, right‐hand polarized precursor waves with a spatial periodicity of about the proton skin length. This is the same type of upstream waves which is generated by oblique, subcritical shocks. The measured period of the magnetic variations (≈40 s) may be explained as Doppler shift owing to the spacecraft motion through the standing wave structure. The fluid results are confirmed by hybrid code simulations. In conclusion, we suggest the Phobos events to be precursor waves resulting from the interaction of the solar wind with charged dust rings along the Phobos orbit.