Rather than go on about Carol and Larry -- since I think most of what needs to be said is there in the links from the previous post -- let us turn our minds to thoughts of the sea. In an abstract for the Lunar and Planetary Science Conference, which will be held in March, a team using the high resolution camera (HRSC) on Mars Express, makes the case that there was a sea the Elysium region of Mars in the very recent past -- ie the last 5 million years.
The abstract was picked up by New Scientist who seem to me to have done a very good job of it. The gist of the story is this: a flood pours out of the ground in the Cerberus Fossae region and drains into a local basin, about 800km by 900km, where its surface freezes and gets covered with ash. While fresh water and volcanic heat keep getting added the system stays in flux, with plates of floating ice being formed and broken up in the flow. When the volcanism ceases, the whole thing freezes; the plates of dirty pack ice are set into a matrix of fresher ice, which unlike the pack ice is not covered with ash.
The dirty pack ice is fairly stable, because of its cover of insulating ash. The cleaner ice in which the pack ice is set, though, starts to sublime -- to turn straight into water vapour. As this ice starts to sublime, its surface gets dirtier, because sediments that were in the water when it froze are left sitting there on the surface after the ice sublimes. As this "lag deposit" of sediment builds up the sublimation slows down.
This seems a pretty good job of explaining what the cameras (HRSC and MOC) see. This sort of "platy" landscape has been seen and discussed before, with lava and mud flows also suggested as explanations. But to act in this watery a way, the lava would have to have incredibly low viscosity. Water really does, at least on first inspection, seem a much better option. If water is the explanation here, then it probably fits for other platy landscapes, too. If this is a fossil sea, then there are more of them.
The open question is whether any of the ice remains. It might all have slowly sublimated away, leaving the lag deposits on its surface draped over what was previously the seabed. Or some of it might still be there. The case for it still being there is that craters in the area seem to be filled in by something, and that the surface is very very flat. Good arguments, but not entirely compelling.
At 800km by 900km, and about 50 metres deep, the putative sea is about the size of Europe's North Sea. Crater counts on the surface put it at about 5 million years old -- with the plates a touch older than the stuff in between (I imagine there are decent sized error bars on that). That's a really respectable body of water to have gush out of the subsurface -- and if there's life in that subsurface, all that water should have carried some of that life up with it. The silty lag deposits on the surface should have little microbial corpses in them -- even if there's no ice left under them; they'd effectively be seabed sediments laid out on the surface. How well the corpses are preserved is of course an open question.
Needless to say, the response to this paper will be fascinating to watch. If the morphological arguments carry the day and it is accepted as evidence for a real sea, then Mars has a new "most interesting place".
After all this excitement, a note on propriety. When New Scientist reported this story, it did so on the basis of the abstract, freely available at the LPSC site, which it followed up with insights from a scientist who was not on the team (the lead author, btw, is John Murray at the Open University). After the New Scientist story hit the web, the abstract had a big red headline added to it to the effect that the material within was under embargo by Nature until mid-March. The inference I draw from this (I've not talked to the principals) is that the work has been accepted by Nature, and Nature sees the abstract as a form of prior publication, which it doesn't want. I can see their point -- but in this case trying to embargo something freely available for all the wired world to see, and which has been reported on entirely legitimately by a good magazine, just seems silly. And refusing to publish the paper now would look pretty silly, too. I'm sure the editors at Nature wish the researchers hadn't published the abstract -- but the paper wouldn't have been accepted by LPSC, where it needs to be presented and discussed, without an abstract. Anyway, this is the way things have turned out, and it seemed to me it would be rather silly not to comment, seeing as the story’s out there anyway.