Like Earth, Mars gets depressed when it’s hit by a space rock.

This image, from NASA’s orbiting Mars Global Surveyor, shows a circular depression near the south pole of Mars.

Also visible, scientists say, are eroding mesas of frozen carbon dioxide, or dry ice. The south polar region of Mars is covered in a cap of dry ice, which until recently hid water ice that scientists now know is beneath.

The eroding carbon dioxide creates landforms reminiscent of Swiss cheese seen in previous pictures. The circular feature might indicate the location of a filled, buried impact crater, said scientists with Malin Space Science Systems, which operates the primary camera on the orbiter.

-- SPACE.com Staff

Credit: NASA/JPL/Malin Space Science Systems