NASA's big announcement today is that NASA's Mars Reconnaissance Orbiter found evidence that strongly supports the longtime theory that salt water in liquid form flows down certain Martian slopes each summer!
The source of the water is still a mystery. Scientists speculate it could be melting ice, an underground aquifer, or water vapor from the thin Martian atmosphere, or a combination thereof. Of course the biggest deal is, that finding water can have major implications for the possibility of life on Mars!