| Mars Global Surveyor's magnetometer/electron reflectometer (MAG/ER) experiment has returned over eight years of observations of low frequency plasma waves produced in the interaction of the solar wind with the Martian ionosphere. Using the MAG/ER data, I identify the properties and physical origins of the waves in the magnetosheath, magnetic pileup region, and ionosphere. I find that the waves in the dayside magnetosheath are predominately mirror mode instabilities produced by plasma temperature anisotropies arising from the draping of the solar wind magnetic field around the ionosphere. The nightside magnetosheath shows evidence for resonant ion instabilities arising from the interaction of the solar wind plasma with the ionospheric plasma. These waves are therefore an indirect observation of ongoing atmospheric loss at Mars. During the large solar storm of October 2003, dramatic changes were observed in the plasma waves present; even the normally placid tail region showed signs of significant wave activity. Coherent oscillations are observed in the ionosphere and are presumably driven by solar wind fluctuations or are associated with field line resonances along crustal fields. |
