Mars’ Heterogeneous South Polar Magnetic Field Revealed using Altitude Vector Slepian Functions

The Mars Global Surveyor satellite mission (1997–2006) provided us with the first ever global coverage of magnetic measurements for Mars. Due to the absence of a core field, the magnetic measurements on the day side have a larger noise component than nighttime measurements. Generally, the lower the measurement altitude, the less signal attenuation, in particular for relatively small scale magnetic features. In its orbit insertion, Mars Global Surveyor flew through the Martian atmosphere at altitudes down to approximately 100 km above the planet’s surface. Figure 1 shows the location of the low altitude (below 200 km above mean volumetric radius 3390 km) nighttime data plotted over the Martian topography provided by [1]. In our contribution we present a model for the Martian crustal magnetic field around the South Pole calculated locally from these highest-quality data. Our approach allows us to reliably resolve finer details than would be possible by diluting the highest-quality data with lower-quality data covering the entire planet.