NASA Mars Recon Orbiter HiRISE Image: Chasma Boreale

A coloured satellite image of a steep cliff at the head of Chasma Boreale on Mars, obtained by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO).

The orbiter peers directly down at a dizzyingly steep cliff face in the Red Planet's polar regions.

The cliff, to the right of the image, is composed of layer upon layer of red dust and pale ice deposits which, like tree rings on Earth, preserve a record of the Martian climate.

Picture: SCIENCE PHOTO LIBRARY / NASA