The Mars Global Surveyor is already earning its keep. It recently sent home images that seem to indicate that liquid water has flowed on the surface of the frigid world within the last few years. While it is impossible to tell from orbit what exactly caused the lighter splotch, it strongly suggests that liquid water burst forth from the gully and flowed down the slope leaving the pictured deposit. Michael Malin of Malin Space Science Systems in San Diego said, "The shapes of these deposits are what you would expect to see if the material were carried by flowing water".
We have known for quite some time that there was still plenty of water on Mars, but it was assumed that most of it was locked up in permafrost, ephemeral vapors, or at the polar ice caps, but this is the strongest evidence yet for underground liquid water deposits. And where there is liquid water there is as strong possibility for life. Of course, no one is expecting to find a thriving underground civilization, but even the presence of microbes or primitive plant life would finally prove, beyond a shadow of a doubt, that we are not alone in the universe. It seems to me that while a Moon base, as NASA plans to establish by 2024, would be cool, a manned mission to Mars might just be a bit more important now. And if, indeed, there are large quantities of liquid water close to the surface, it just became a lot more feasible, since liquid water can be converted into both oxygen and hydrogen, two primary components for human survival...and rocket fuel. Go here for the full story.