A South Polar Pit on Mars or an Impact Crater?

Observation from NASA's Mars Reconnaissance Orbiter of Mars's South Pole. Credit: NASA/JPL-Caltech/Univ. of Arizona

This observation from NASA's Mars Reconnaissance Orbiter show it is late summer in the Southern hemisphere, so the Sun is low in the sky and subtle topography is accentuated in orbital images.

We see many shallow pits in the bright residual cap of carbon dioxide ice (also called "Swiss cheese terrain"). There is also a deeper, circular formation that penetrates through the ice and dust. This might be an impact crater or it could be a collapse pit.

This is a stereo pair with ESP_049945_0930.

The map is projected here at a scale of 50 centimetres (19.7 inches) per pixel. [The original image scale is 49.7 centimetres (19.6 inches) per pixel (with 2 x 2 binning); objects on the order of 149 centimetres (67.3 inches) across are resolved.] North is up.

Credit: NASA/JPL-Caltech/Univ. of Arizona