How long has the Martian surface remained unchanged, compared to Earth and other planets and moons?
By assuming that meteor impacts that cause craters happen at a constant rate but are then eroded away, we can estimate how much resurfacing a world has. Earth s craters disappear quickly (in thousands or millions of years, whereas its moon, now that its volcanoes are gone, has nothing to erode craters except for smaller meteors. The data from Viking Orbiter data suggests that some Mars surfaces hardly change over billions of years, much longer than on stormy Earth, icy Europa, or volcanic Io. New MGS data shows that the surface is changing all the time at a finer scale, but no systematic crater count has been done yet. Perhaps you ll get to help with that question.
