Dust storm grounds Mars rover

ST. LOUIS, Jan. 3 (UPI) -- The upgraded Spirit rover marked its third anniversary on the Martian surface, riding out a dust storm, rover scientists in St. Louis said.

Spirit's instruments last week detected hazy conditions due to a dust storm churned fine dust grains high in the atmosphere, NewScientist.com said. Because storms can prevent sunlight from reaching the planet's surface, they could be dangerous for the rovers, which rely on solar power to generate electricity.

Controllers on the ground stopped Spirit, which landed on Mars in January 2004, from gathering information on an igneous rock named Esperanza, moving it to a location where it could capture the maximum amount of sunlight available.

"We had to boogie on out of Esperanza," says Ray Arvidson, deputy principal investigator for the rovers' science instruments at Washington University in St. Louis.

Once the weather improves, Spirit will likely examine another vesicular basaltic rock similar to Esperanza, scientists said. These rocks have large holes created by cavities of gas in molten lava, which gives them a sponge-like appearance.