Hard on the heels of the water-on-the-Moon announcement comes news of water on Mars (there's also a press release). Now, we already know there's water ice on Mars; it's been seen in a zillion places. What's cool about this is that there's a lot of it, and the water is incredibly pure: less than 1% of it is made up of dirt mixed in. That's probably better than I get out of my tap at home.
Well, not really. But still. Here's a shot of the ice:
This picture, taken in November 2008, is by the awesomely awesome HiRISE camera on board the Mars Reconnaissance Orbiter, which has seen several of these patches, where ice just beneath the surface is excavated and ejected by an impact event. They all appear to be craters formed from recent impacts, and by "recent" I mean recent: the one shown above was not there in early 2008.
At these latitudes (40° - 60° north), ice can't last long, so more images taken should show the ice sublimating (going from a solid right to a gas, just like the hallway ice skating rink in "Real Genius"). By the way, the crater you see there is just 8 meters (26 feet) across. The whole image is only 50 meters across!
What this means is that Mars has ice, nearly pure ice, too (other instruments on board MRO can measure the chemical composition of the surface), just under the surface in many places, possibly even in a broad sheet hundreds of kilometers across. The ice ranges in depth from 1 cm to 10 meters deep.
That's a lot of water. Far more than on the Moon, and it looks like it's easier to get to as well.
Well, easier once you're there. At best, Mars is a hundred times farther away from the Moon. That's why I think we need to wait a while before we go back to Mars; the Moon is easier to go to (heck, some near-Earth asteroids are easier to get to) and what we learn doing that on a regular basis will help us go to Mars.
In the long run I'm all for colonizing Mars, but I'd like to make sure we have the engineering, the guts, and above all the funding to do it.