Martian cratering 9: Toward resolution of the controversy about small craters

The Malin et al. [Malin, M.C., Edgett, K., Posiolova, L., McColley, S., Noe Dobrea, E., 2006. Science 314, 1573–1577] report of ongoing production of decameter scale primary craters matches within an order of magnitude the crater production curves of Hartmann [Hartmann, W.K., 2005. Icarus 174, 294–320], and appears to contradict models that say our curves grossly overpredict primary production. Nonetheless, such models may still predict correct order-of-magnitude secondary production. The new observations, if correct, require geologically recent martian surface modification in some areas, on timescales comparable to the cycles of obliquity changes, suggesting episodic martian climatic/environmental change driven by the obliquity cycles.