Rupes Tenuis annotated nadir view

ESA’s Mars Express orbiter imaged the snow-laden region of Rupes Tenuis on the martian north pole on 29 July 2008.

Rupes Tenuis is located at the southern edge of the martian north polar cap, approximately 5500 km northeast of the Tharsis volcanic region.

The images are at about 81° north and 297° east and have a ground resolution of approximately 41 m/pixel. They cover an area of about 44 000 km2, almost as large as the Netherlands.

Darker material, mostly dust, is brought in by the wind, and snow and ice are deposited in colder periods. This interplay between sedimentation and ice formation forms the Polar Layered Deposits visible clearly in the images (1).

An incision visible at top-centre of the image is more than 100 km long (2). Such curved incisions are common on the edges of the polar caps. Why such structures form is still not known. Chasma Borealis, visible on the right-hand side of the image, is one such incision.

Small, cone-shaped mounds (3) have long been interpreted as being volcanic in origin. New data suggest that some of the mounds may be remnants of older material that covered the area earlier. This material may have been more resistant to erosion, forming the mounds.