Geologic evolution and cratering history of Mercury

Among the terrestrial planets, Mercury is the smallest and has the highest bulk density. Mercury exhibits a lunar-like surface, shaped by impact basin s and craters. Rapid cooling and contraction as well as tidal despinning ha ve resulted in a large inventory of tectonic scarps and faults visible on t he surface. With plans for new orbiter missions to this intriguing planet t aking shape, this paper presents a summary of our current knowledge on Merc ury's geology and cratering history. On the basis of improved data on aster oid populations and crater scaling, we updated the time stratigraphic seque nce for the planet and made new estimates for the time of formation of impa ct basins such as Tolstoj and Caloris, which generally are now thought to b e younger than in previous estimates. In order to advance our understanding of the geology of the planet, imaging experiments on future missions must fill the gap in the global coverage left by the Mariner spacecraft, and inc rease the global multispectral spatial resolution to at least 100 m/pixel. Locally, the image resolution must reach approx. 10 m/pixel. Also, stereo t opographic models with global and local resolutions of 200 and 20 m, respec tively, are required. (C) 2001 Elsevier Science Ltd. All rights reserved.