Electron plasma waves beyond the Marsʹ bow shock: The PWS/Phobos-2 observations Original Research Article

Electron plasma waves are commonly observed at or near the ambient solar wind plasma frequencies beyond planetary bow shocks. They are correlated with times when the interplanetary magnetic field is connected to the shock front, i.e., when entering the electron foreshock region in which suprathermal electrons accelerated at the bow shock are streaming back from it. Such electron plasma oscillations have been observed upstream of the Martian bow shock by the plasma wave system, PWS, on the Phobos 2 spacecraft. Phobos 2 has been operational in Martian orbits for almost two months. From January 29 to March 27, 1989, the Martian shock was crossed at least a hundred times and the upstream region extensively probed. The aim of this paper is to present the characteristics of the Martian electron plasma waves and to compare them with the Earthʹs and Venusʹones.