Parts of the residual, or permanent, south polar cap show a pattern reminiscent of sliced Swiss cheese. This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image taken August 2, 1999, at the very start of southern spring. Two layers are evident on the frost-covered surface — a brighter upper layer into which are set Swiss cheese-like holes, and a darker layer underlying the Swiss-cheese pattern.
Nothing like this exists anywhere on Mars except within the south polar ice cap. The image is about 1.9 miles (3 kilometers) across.
Some portions of Mars’ south polar residual cap exhibit long curving troughs instead of circular pits. This “fingerprint terrain” seems to form in a layer of material different from that involved in creating Swiss cheese.
This MGS MOC image, acquired August 4, 1999, in the early austral spring shows a series of long, narrow depressions. Scientists think they formed through collapse and subsequent widening as ice sublimated.
Fingerprint terrain is found only in the Red Planet’s south polar region. This image is about 1.9 miles (3 km) wide.
Mars Odyssey’s THEMIS instrument took this 5.5-mile-wide (9.9 km) image June 25, 2003, at the start of the southern spring season. This false-color image highlights layers in the ice cap. The dark spots fringing the cap appear only when the Sun first lights the ice.