Water on Mars

It's quite public now that there was fluid water on planet Mars. But now, by accident (as most scientific discoveries occour...) the Rover Spirit (whose mission ended up about 3 years ago, but is still going) having a malfuntion on one of her wheels, dragged some dirt and discovered an under layer of dirt which after x-ray analize, turned out to be Silica, a chemical component that gives shape to our Quartz and to our mirrors, and that needs water for it's formation. See the note