This perspective image of a fractured crater near Valles Marineris on Mars was obtained by the High Resolution Stereo Camera (HRSC) on board the ESA Mars Express spacecraft.
The image was taken during orbit 61 in January 2004 with a resolution of 12. 5 metres per pixel. It shows part of a cratered landscape to the north of the Valles Marineris, at 0.6? S latitude and 309? E longitude, with this crater having a fractured base.
This crater has a rim diameter of 27.5 kilometres and is about 800 metres deep. It is not known yet how these fractures are generated. On Earth, polygonal fractures may occur in contracting material, which breaks at weak zones. For example, we may see this appearing in cooled lava, dried clay or frozen ground.
Original Source: ESA News Release