Curiosity found water on Mars.
Tiny little droplet molecules bound to other minerals. But Curiosity found water on Mars, at the rate of about two pints per cubic foot of soil, about 2% of the makeup.
That's the good news, and it's very good news. The bad news is that they also found 0.5% makeup of a perchlorate of some type they never got into very much in the Guardian writeup, and that perchlorate would be enough to screw with your thyroids.
Full analysis is here.