Ongoing NASA press conference, on as I write, Slashdot quote “Drenched with Water”:
They are saying that the crater that the second rover has landed in has convincing evidence that it was once drenched or covered in liquid water. They cite the tiny spherules, odd holes in the rocks, sulfur in the spectrometric analyses, and evidence of an iron sulfate hydrate (a hydrate is a chemical compound which includes water molecules in the crystal lattice).
Update: Astonishing! Lots of salt, it sounds like there were large seas on Mars. “Significant liquid water”.
Update: They plan to send the Rover a good distance, to examine a particular crater – it might not make it.
Update: “We have nailed a new aspect” How extensive is this evidence of ancient ground water? “How long did water soak the rock?”
“Now we finally have examples of stuff we really want to bring home”
Update: “We cannot tell you if these rocks were laid down in a pool of water or sea” “The best way to get age is to bring a rock back”
Spirit will travel 100 metres a day, and take up to several weeks before it reaches ‘Endurance’ crater.