Mars' Induced Magnetotail at Mars Global Surveyor Mapping Altitudes

Previous studies have shown the dual--lobed nature of the night--side external field at Mars caused by the draping of the Interplanetary Magnetic Field (IMF) around the planet. For most of it mapping phase orbits (360--420 km altitude) Mars Global Surveyor (MGS) collects magnetic field and electron reflection data in either one or the other of these lobes depending on the orientation of the IMF. However, occasionally the geometry is such that MGS passes through both lobes and a current sheet which separates them, indicated by a sharp reversal of the field direction and a small increase in electron fluxes. Vector magnetic field data from 8 March 1999 to 6 January 2004 have been visually inspected in order to compile a list of all such magnetotail crossings, and these events have been characterized according to IMF strength, IMF field direction, and incident solar wind pressure (calculated using a proxy method).