Keywords: mars nasa mro jpl science landscape geology monochrome texture rock outdoor abstract Secondary Craters: Secondary impact craters are both interesting and vexing, but can be used to constrain the age of the surface where they fell. NASA/JPL/University of Arizona (www.uahirise.org/ESP_046876_1465) Secondary Craters: Secondary impact craters are both interesting and vexing, but can be used to constrain the age of the surface where they fell. NASA/JPL/University of Arizona (www.uahirise.org/ESP_046876_1465) |