Hi, everybody, this will be my first post here; I've been wondering about this and have also posted it over at the Bad Astronomy board.

While browsing through the abstracts from the 36th Conference on Lunar and Planetary Science (immensely fun), I came upon this paper (page 27, entitled "Origin of Layered Rocks, Salts and Spherules at the Opportunity Landing Site on Mars: No Flowing or Standing Water Evident or Required"). It asserts that the evidence for a salty sea at Meridiani spotted by Opportunity has been misinterpereted. What do you think? Personally I get the sense that this is the 1 guy out of 100 who doesn't share the mainstream scientific opinion, but I'd be interested if someone more versed in Mars geology than I would be willing to comment on it.

That said, this looks like an interesting place- glad to see that I can get some info on Spirit and Opporutnity other than the NASA press releases! (a.k.a. every three weeks we learn how Spirit and Opporutnity are "unlocking the secrets of the solar system").

I was convinced a long time ago about free flowing water on mars.
When you got Canyons the length of the states, is enough proof for me.

That was an interesting abstract. The authors offer a quite diverse set of observations and hypotheses, many of which question coventional interpretations of recently acquired Martian data.

They are suggesting that the Meridiani sediments were deposited as "distal base surge deposits related to meteorite impact into an ice, brine, and salt-rich regolith, rather than evaporites of an acid sea."

One could imagine a large number of scenarios that could have produced such finely laminated and crossbedded sediments containing interesting diagenetic alterations. I don't think we have remotely collected enough Martian data to definitively settle the issue.

Personally, the rocks appear to me to be dirty evaporites...a mixture of physical and chemical, depositional processes. The processes that I wrestle with are those that may be uniquely Martian.

I'm sure a lot of these theories will be challenged, which is as it should be. They're still analyzing the data from the Viking landers and getting new conclusions; I'm sure that the data from the rovers will be thoroughly analyzed by many people, but the full process will take time. NASA probably is under pressure from their PR department to come up with an explanation fast. The pictures are available, so the people want an explanation. And, these days, we want it now!

I agree. Patience is not in the vocabulary of most people nowadays, while it is the most important aspect of thorough analyses. But, it is definately a strong article and also makes me doubt about the acid sea. In other words: i get the feeling that the evidence for a sea during a long period of time isn't as strong as NASA claimed it to be in the press conference last year. I don't say there wasn't a sea, but i certainly can't say that there was !

Marcel.