The Opportunity Rover, one of the most successful explorers in history, has added another remarkable discovery to its résumé. Opportunity has found a type of clay that is deposited in water – not just any water, but water with the right chemistry for our kind of life. In the words of Project Manager Steve Squyres, "This is water you could drink."
What's the big deal? Haven't our intrepid Mars rovers already found lots of evidence for ancient Martian water? Yes, they have. But this discovery is different.