Mars does not have an active dynamo today. However, rocks in Mars’ crust have remanent magnetic fields from a dynamo in Mars’ ancient past. The crustal magnetic fields are strongest in the southern hemisphere and correlate with the hemispheric crustal dichotomy on Mars. We have shown that the formation mechanism for the crustal dichotomy (either a giant glancing impact or hemispheric mantle circulation) can produce a single-hemisphere dynamo concentrating magnetic fields in the southern hemisphere. This may explain the observed pattern of crustal magnetic fields on Mars. Relevant papers by my group and collaborators include:

• Stanley, S., Elkins-Tanton, L.T., Zuber, M.T., Parmentier, E.M., Mars’ Paleomagnetic Field as the Result of a Single-Hemisphere Dynamo, Science, 321, 1822-1825 (2008).

I am also currently a Co-I on the Mars InSight mission studying the ancient martian dynamo.