Analyzing Magnetic Field and Electrical Current Profiles of the Day Side and Terminator of Mars Using Data from Mars Global Surveyor (MGS)

Abstract:

Mars does not have a global magnetic field, so the interplanetary magnetic field (IMF) can impact the upper atmosphere and induce currents in the Martian ionosphere. During aerobraking maneuvers, Mars Global Surveyor (MGS) made over 1000 passes through the Martian ionosphere. During the aerobraking phase, MGS measured the local magnetic field in the ionosphere. From measuring changes in the magnetic field, we can calculate the ionospheric currents. By only using measurements where the radial component of the magnetic field is zero and making some assumptions about the gradients in the magnetic field, we are allowed to classify data that meets those conditions as “good” data and calculate horizontal currents in the ionosphere. We focus on data taken over regions of Mars that had negligible crustal magnetic fields to simplify our analysis. The data being analyzed is observed at a maximum altitude of 250 kilometers with a solar zenith angle (SZA) range of 0 degrees to 50 degrees for the day side and 50 to 130 degrees for the terminator. For the day side of Mars, it was found that 24.06% of the data observed was usable data under the initial parameters that were set for “good” data. For the terminator, it was found that 32.08% of the data was usable. The currents that are computed using these “good” magnetic field profiles can give us insights into how the changing solar wind and interplanetary magnetic field can effect the upper atmosphere of mars. For example, induced currents can lead to Joule heating of the atmosphere potentially modifying the neutral dynamics.