Steve Squyres has a podcast featured on nasa.gov (transcript here). He talks exclusively about Opportunity and the 'big picture' achieved by all the work done in Endurance (timed, no doubt, to coincide with the new papers being published now).

They mention a part 2, which will be posted next week, hopefully featuring some Spirit news and observations.

Quotes of note:

"...there was water beneath the ground, the water was probably very acid, it was probably sulfuric acid, the water table fluctuated, it would go up and it would go down. We don’t really understand what caused the water table fluctuations, but we see very, very clear evidence for it. Sometimes the water would rise all the way to the surface and you would actually have exposed water at the surface that might have lasted only for a very short period of time and the water would evaporate away and leave salts behind."

"...Mars is a place where there was water, there was water beneath the surface. We haven't found any evidence for waves, we haven't found any evidence for deep water, we haven't found any evidence for rainfall. That doesn't mean none of those things happened. But what we have found has been evidence for a much more limited sort of water activity where water just comes to the surface for brief periods. It could have been very different on other parts of the planet. "

Ah, interesting! Thanks for posting slinted

Nico

An excellent overview.

Just one note:

I think it is important, imperative even, to view Oppy's findings in context of the new ones from Mars Express this week. Yes, the geological age shown by Oppy was salty and acidic, but it also seems that, in the previous time period, as shown by Mars Express (including in Meridiani) and outlined by ESA, the water was non or less acidic, stably present and abundant, too, whether still mostly as groundwater and aquifers or ? Something happened, as the ESA team put it, to cause the water to become more acidic, some kind of global climatic change.

The phyllosilicates / clay minerals found by Mars Express are one of the key findings of any mission, I feel. A lot of the media and science media coverage I've seen this week so far covers the new MER findings, but not the Mars Express findings (or often much briefer), re the phyllosilicates in particular I mean. Some of the reporting does seem biased.

I hope Opportunity can look at deeper layers such as in Victoria crater; people may now assume that the sulphates represent the entire history here, but if the Mars Express team is correct, then it is only one part of a longer and more varied story.

Ummm.... what about the cross-bedding in the rocks at Eagle Crater? I thought that was supposed to be foolproof evidence of the sand grains being deposited by wave action?

-the other Doug

QUOTE(slinted @ Dec 3 2005, 04:27 AM)
"...We haven't found any evidence for waves.. "
*

dvandorn replied:
"Ummm.... what about the cross-bedding in the rocks at Eagle Crater? I thought that was supposed to be foolproof evidence of the sand grains being deposited by wave action?"

Frankly, that always was a very dubious interpretation... well, shall I say a 'non-unique' interpretation. They were over-eager, and I wouldn't be at all surprised if they didn't now think it was pushed too far.

Phil

Cross-bedding is also produced by wind -- which would presumably be the most likely interpretation on Mars.

--Emily

Cross-bedding was interpreted as having been created by flowing water, not waves. Periodic surface water could have flowed. Waves would have required a long-standing, deep water feature.

"Sometimes the water would rise all the way to the surface and you would actually have exposed water at the surface that might have lasted only for a very short period of time and the water would evaporate away and leave salts behind."

Which specific locations that have been studied is he referring to? Also, would a few small locations between flat stones in which the soils looked water-leveled be considered as evidence of water briefly on the surface? And is it possible that the linear depressions such 'Anatollia' are evidence of water very near the surface, which dissolved out salty deposits, causing a collapses?

Yes, the festoon cross-bedding is very indicative of flowing water rather than wind action

Yes, it is... the question, though, is whether the specific pattern seen in the Eagle crater outcrop actually is festoon cross-bedding or not. That's not nearly as certain as was first suggested. I'm not saying it isn't, but it should not be regarded as a solidly established fact.

Phil

Just as Mars is a dynamic system which has had a variety of process operate to produce the landscape we see today, our understanding of these processes and the details of these processes evolves with the data we are collecting. Our understanding of the lithology, stratigraphy, geomorphology and the other '-ologies' changes with new information. We have a jigsaw puzzle laid out on the table before us and as we get more puzzle-pieces in front of us the better we can see the big picture. It is clear that water and the weathering of basalts is the basis for much of what we see, but many of the details are not clearly seen.

Yet...

--Bill

Somehow an interview with Steve Squyres without the sound of wind blowing, is just not the same.

Part 2 is now online!

Podcast:
http://www.nasa.gov/mp3/139029main_squyres_2.mp3

Transcript:
http://www.nasa.gov/multimedia/podcasting/...s-20051205.html

Re the lack of carbonates, what about the traces that Spirit found at the beginning of the mission, and the low concentrations globally as reported earlier?:

http://marsrovers.jpl.nasa.gov/newsroom/pr.../20040109a.html

I'd like to get Squyres' take on the phyllosilicates / clay minerals that Mars Express found (including in Meridiani)... again, the acidic water was a harsh environment, as documented now by Opportunity, but there was also apparently a less harsh (and still very wet) environment either just before that or coinciding. As Bill said, it's a jigsaw puzzle...

Good interview.

One comment:

"Mars is a planet where the groundwater in many instances is sulfuric acid, and some very interesting things can happen when the sulfuric acid interacts with..."

Water is water and if it is in the ground is is groundwater. You don'thave groundwater that is sulfuric acid, but you can have acidic groundwater. Water is "the univeral solvent" and when in contact with the rocks of the aquifer it can and does pick up dissolved constituents such as sulfates, carbonates and metals. Groundwater can become acidic in this way; typically, the oxidation of iron sulfide yields hydrogen ions, sulfates and free iron.

There may be carbonates in the lithosphere; remember, we've only looked in a few small windows into the subsurface.

--Bill

What kind of atmospheric conditions would be a pre-requisite? Atmospheric pressure is lower, tides are less substantial... And tides require extremely huge water bodies.

I can't imagine that most of the crossbedding we've seen is from anything but flowing water. The fine-scale stuff is not wind, and it's not oscillating water.

I really also have trouble with sulfuric acid in the environment. I would think sulfurous acid would be far more likely.

Now phyllosilicates are real news. Anyone have some links to that?

Thanks, Paul, for the link to part 2. I just knew someone would remind us.