nai

Project Progress

The magnetic field generated by the early Martian dynamo may have shielded to some extent the early Martian atmosphere from solar wind erosion. The history of planetary dynamos may thus directly relevant to the history of surface liquid water stability and hence habitability We have been improving constraints on the history of the Martian dynamo, both when it existed and its strength. The Mars Global Surveyor magnetometer and electron reflectometer (MAG/ER) data were used to create a global map of crustal magnetic field magnitude at 180 km above the Martian surface. Using this map, the magnetic signatures and surface ages of volcanoes and large impact basins are being analyzed in detail and modeled to constrain the ambient magnetic conditions which existed during their formation and later alteration. Using newly identified quasi-circular depressions identified by H. Frey (NASA Goddard), we have been able to provide tighter bounds on the termination of the dynamo. Our results suggests the dynamo ended over a short period, < a few 10s of millions of years. Prior to its termination, the field strength does not appear to have changed significantly. We find no compelling evidence that the martian geodynamo restarted.