Characteristics of Fresh Martian Craters as a Function of Diameter: Comparison with the Moon and Mercury

Abstr. act. Martian craters defined as fresh on a more comprehensive analysis of the morphologies the basis of morphologic parameters have been anof fresh craters on Mars and to compare the charalyzed for the presence and abundance of various acteristics and size distribution of morphologic morphologic features as a function of size. features of martian craters with those on the Bowl-shaped craters dominate the fresh crater Mmon and Mercury. population below about 15 km. The onset of cenBased on criteria presented below, 33,810 tral peaks occurs at about 5 kin. Craters above fresh craters were chosen from a population of about 15 km often have terraced walls, central 46,559 martian craters of all sizes and morphopeaks, and h,,mmocky floors; at diameters of 40 km logies. The data base consists of a catalog of and greater, these features dominate fresh marall craters visible on Mariner 9 A frames. Cratian crater morphology. Central peak onset ter location, rim crest diameter, and a series occurs at smaller diameters on Mars and the Moon of morphologic features, as well as several other than on Mercury, and terrace onset occurs at simiparameters, are recorded for each of the craters. lar diameters on the Moon and Mars, but at larger The procedures for recording the data and the dediameters than on Mercury. Since Mars and Mertails of the morphologic classification scheme cury have a similar surface gravitational acceleare presented elsewhere (Arvidson et el., 1974; ration (greater than twice that of the Mmon), Arvidson, 1974). Craters classified as volcanic gravity-controlled crater features should appear on the basis of these morphologic parameters have at similar diameters on the two planets. However, not been included in this study. the differences in onset and abundances of cen-