Discovery of a 450 km diameter, multi-ring basin on Mars through analysis of MOLA topographic data

Abstract

Mars Orbiter Laser Altimeter (MOLA) topographic data have revealed a previously unknown, 450 km wide, 2 km deep basin centered at 30N, 312W near the Phison Rupes. This basin, as large as and deeper than the obvious Cassini impact basin located 1000 km to the SW, is not apparent in the existing but good quality Viking imagery. Gridded MOLA data show the feature as a closed depression. Based on analysis of slope breaks readily visible in two MOLA profiles, we suggest this Phison Rupes Basin has three topographic rings with diameters approximately 350, 455 and 670 km. These rings outline a region of lower impact crater density and smoother inter-crater plains. Similar previously unknown features may exist elsewhere on Mars, and MOLA topographic data may be able to locate them. Copyright 1999 by the American Geophysical Union.