[Miss Marple]

No, they said there had been liquid water there at one time.

[John H K]

Err, yes, at one time, not currently.

[monkapotamus]

This is nothing they haven't known for about 30 years. Several Viking photos showed a water spout which changed patterns when re-photographed seconds later. They are trickling the information out like a time release capsule to get us used to the idea before they spring 'we found life' on us.