Impact cratering has affected the surfaces of all bodies in our Solar System. These short-duration but energetic events can drastically affect the regional and occasionally the global environment of a planet. The cratering record is better preserved on Mars than on Earth due to longer-term stability of the Martian crust and lower degradation rates. Impact cratering had its greatest effect early in Solar System history when bombardment rates were higher than today and the sizes of the impacting objects were larger. The record from this period of time is largely lost on Earth. High bombardment rates early in Solar System...