Although most people would consider Mars a stagnant planet, new research reveals a complex and climatologically diverse planet in which ice ages have repeatedly come and gone and shaped the Martian landscape. Under current Martian conditions, H2O in the polar caps is stable, but as the planetary spin axis changes (increases), ice in the polar cap becomes unstable, sublimates to vapor, and ultimately nucleates as snow on dust particles at low latitudes. At a spin-axis tilt of 45° (today Mars' spin-axis tilt is ~25°), water vapor is fully transported to the tropics, where it forms equatorial glaciers as much as 180,000 km2 on the northwest flanks the of Tharsis volcanoes. At lower spin-axis obliquities, ~30-35°, dusty snow "mantles" the Martian surface down to ~30° north and south of the equator. The last such "mantling' occurred between 2.1 and 0.4 million years ago. Today, Mars is in an interglacial period, and water vapor is subliming from buried-ice deposits and moving back to the poles.
Boston University's Antarctic research group has been instrumental in mapping and interpreting the origin and evolution equatorial mountain glaciers on Mars. The team was the first to identify cold-based glaciers on Mars, and to develop models for the formation of ice-rich polygons and glacial features that today occur at a variety of latitudinal bands (and ages) on Mars. The team's numerical modeling and field studies of buried-ice deposits in Antarctica are used to explain landscape evolution during Mars' current interglacial period. Collaborating with the NASA Phoenix Lander Team, geomorphologists at BU will be among the first to interpret images taken from the Phoenix spacecraft, which touches down in icy terrain, 60°N Latitude, this May. The presentation outlines how geomorphic studies of landscape change in the Dry Valleys of Antarctica shed light on climate change on both Earth and Mars.