Paleopole Investigation of Martian Magnetic Field Anomalies

Kurzfassung

Ever since the start of the space era, magnetometer carrying spacecrafts were sent to measure the magnetic fields of the Earth and other terrestrial planets in the solar system. The first attempt to measure the magnetic field of Mars was during the flyby of the Mariner 4 spacecraft and it was concluded that unlike Earth a current core dynamo is absent. Even though magnetometer carrying spacecrafts approached Mars in the following decades, it was not until 1997 that the Mars Global Surveyor (MGS) mission discovered a strong remanent magnetic field originating from the Martian crust. Ever since, the results of MGS were integrated in local and global magnetic field models, which were eventually used for paleopole reconstruction. By comparing all paleopole investigations since the year 2001 it was revealed that determined paleopole locations are widely spread all over the Martian surface and it was therefore an objective of this study to find the reason for the spread and give an estimate of uncertainty for paleopole locations on Mars. From synthetic tests, as well as tests on real data, it can be concluded that perturbation in the measured magnetic signal causes residuals in the determined paleopole location, which explains the spread found in earlier studies. Eight Martian magnetic field anomalies were investigated in detail and the determined areas of admissible paleopole locations show a mean surface coverage of 35.5%. These areas constrain paleopole locations to either the northern or southern hemisphere as well as an area in the mid-latitudes. It could therefore be concluded that Mars underwent at least one polar reversal and an event of true polar wander in its past.