Nestled within the fractured rim of a vast impact basin on Mars are valley floors dusted in frost.

At 2200 km wide and up to 9 km deep, the Hellas Basin is the largest impact crater on Mars. This scene, captured on 6 December 2015 by ESA’s Mars Express, focuses on a portion of the western rim of the basin.

This region spans a height difference of over 6000 m, stepping down like a staircase from the basin’s fractured, terraced rim to its flat, low-lying floor that is covered in frost or ice.

The surface expression of numerous valley-like features can be seen below the icy covering, indicating a flow of material towards the catchment areas on the floor of Hellas.

For example, towards the centre of the image, a glacier-like flow has carved a valley through the terraced topography, transporting and dumping material into the basin in a fan structure.