PASADENA, Calif. To celebrate the Mars Global Surveyors third year in orbit around the Red Planet, NASA has released an image the probe recently snapped of a Martian dust storm a billowing front that strongly resembles a Saharan storm seen earlier this year on our own planet.

The Global Surveyors Mars Orbiter Camera, operated by Malin Space Science Systems, caught the Martian storm in the act on August 29, while it was moving as a front, outward from a central jet near the planets north pole.

Such storms are common on Mars in the spring, when the frozen carbon dioxide that caps the planets poles sublimes (a direct change of state from a solid to a gas). As the carbon dioxide sublimes, it boosts the planets atmospheric pressure, allowing it to hold on to more dust and for longer periods.

Furthermore, sharp temperature contrasts between frost-covered and frost-free terrain sparks, give rise to strong winds on Mars, which can whip up dust storms that often can envelop the entire planet.

The August 29 Mars storm, seen here in the reddish image, compares to a Saharan storm NASAs SeaWIFS instrument imaged here on Earth on February 26. The terrestrial storm shows a storm of Saharan sand blowing 1,000 miles (1,600 kilometers) out over the Atlantic Ocean, off the coast of Northwest Africa.

Scientists are studying the global impacts such dust storms have on Mars, where they influence the formation and dissipation of seasonal frosts, and on Earth, where they play a role in everything from Atlantic hurricanes to the health of Amazon rainforests.

NASAs Mars Global Surveyor arrived at Mars on September 12, 1997. It is currently NASAs only functioning spacecraft at Mars. However, the agencys Mars 2001 Surveyor, another orbiter, will join it at the Red Planet on October 20, 2001.