Water on Mars?

A photo released by NASA ,shows a patch of bright-toned soil ...

(AP) - A photo released by NASA ,shows a patch of bright-toned soil found by the Mars Rover Spirit so rich in silica that scientists propose water must have been involved in concentrating it. The silica-rich patch, informally named 'Gertrude Weise' after a player in the All-American Girls Professional Baseball League, was exposed when Spirit drove over it during the 1,150th Martian day, or sol, of Spirit's Mars surface mission (March 29, 2007). One of Spirit's six wheels no longer rotates, so it leaves a deep track as it drags through soil. Most patches of disturbed, bright soil that Spirit had investigated previously are rich in sulfur, but this one has very little sulfur and is about 90 percent silica. (AP Photo/HO/NASA)