Magnetic Fluctuations in the Martian Ionosphere: Electrical Discharges, Solar Wind Perturbations, or Both?

Using Mars Global Surveyor magnetometer data, we present observations of magnetic fluctuations in the Martian ionosphere in the ~ 1 to ~ 16 Hz range. We find sharp spectral features in many of the orbits and across a variety of ionospheric altitudes. Some of the observed features are seen at altitudes below the ionospheric peak and have frequencies similar to those expected for the resonances theorized to be created by electrical discharges in dust storms (aka Schumann resonances). Other possible interpretations include resonances created by the solar wind's interaction with the ionosphere. We discuss how future observations from the MAVEN spacecraft will help clarify the situation.