NASA/JPL/Malin Space Science Systems

In recent years, scientists have watched frozen carbon dioxide disappear from Mars' southern polar cap, a possible sign of climate change on the Red Planet. A new image, released this week, shows some of the bizarre results.

This photo from NASA's Mars Global Surveyor shows the "Swiss cheese" pattern caused by the melting. Scientist say the pits expand at a rate of up to 10 feet (3 meters) each Mars year in some places, as the so-called "dry ice" sublimates into the atmosphere. The process is destroying the the upper 26 feet (8 meters) of the southern polar cap. In fact, that consistent depth of the pits led to an important discovery announced earlier this year: The floors of the pits are made of frozen water, which means Mars has much more water ice than previously imagined.

The picture covers an area about a half-mile (900 meters) wide near 87.1°S, 93.7°W. Sunlight illuminates the scene from the upper left. [Where is Mars?]

-- Robert Roy Britt