Wow, that's like three puns in one title.
Anyway, scientists have revealed they have found large amounts of carbonates (minerals containing CO3 in them) in rocks on Mars. That's kind of a big deal: it's been expected that a lot of rocks would have this compound in them, because there's lots of carbon dioxide afoot there, and plenty of evidence that Mars was once wet. Those two ingredients lead to carbonates. Yet the rocks looked at closely by the rovers have been strangely devoid of them. For the rover Opportunity it's not all that strange; the water on that part of Mars was acidic, and that makes carbonates tough to form. But Spirit is on the other side of the planet, and it was expected it would find carbonates all over the place. Well, turns out it finally has. Some rocks it examined back in 2005 are loaded with carbonates, ...
