The Global Topography of Mars and Implications for Surface Evolution

TLDR

Mars Orbiter Laser Altimeter data provide a high‑accuracy global topographic map of Mars. The planet’s topography is dominated by a low northern hemisphere, the Tharsis province with two broad rises, and the Hellas impact basin, whose excavation raises southern elevations and forms a scarp; the northern depression is a long‑wavelength internal feature, the planet has three major drainage centers with the northern lowlands largest, and polar cap volumes limit present surface water to 3.2–4.7 million km³.

Abstract

Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad rises. Material excavated from Hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary. The present topography has three major drainage centers, with the northern lowlands being the largest. The two polar cap volumes yield an upper limit of the present surface water inventory of 3.2 to 4.7 million cubic kilometers.