Almost 40 years ago, NASA's Mariner 9 spacecraft relayed to Earth the first video images of Mars' northern polar ice cap, revealing a strange pattern of spiral swirls that has puzzled scientists ever since.

PASADENA, Calif., May 26 /PRNewswire-USNewswire/ -- Data from NASA's Mars Reconnaissance Orbiter (MRO) have helped scientists solve a pair of mysteries dating back four decades and provided new information about climate change on the Red Planet. (Logo: http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO) The Shallow Radar, or SHARAD, instrument aboard MRO revealed subsurface geology allowing scientists to reconstruct the formation of a large chasm and a series of spiral troughs on the northern ice cap of Mars.

Scientists have reconstructed the formation of two curious features in the northern ice cap of Mars—a chasm larger than the Grand Canyon and a series of spiral troughs—solving a pair of mysteries dating back four decades while finding new evidence of climate change on Mars.