MICROCRATERS ON MARS - EVIDENCE FOR PAST CLIMATE VARIATIONS

Mars climate models predict hundredfold or greater variations in the mass of the Martian atmosphere due to large amplitude variations in Mars' obliquity through time. The production rates of impact craters on the Martian surface should be greatly affected by these atmospheric mass variations. We have constructed a simulation of the meteor bombardment of Mars which shows that during periods of the lowest theoretical atmospheric mass, the production rates of centimeter-sized hypervelocity impact craters are increased significantly. These results imply that limited in situ observations of microcraters visible on Martian rock faces could validate major aspects of the astronomical theory for climate change on Mars.