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NASA Says Mars Rocks Formed in a Salty Sea
NASA has made another announcement, live on NASA TV, regarding the discoveries of the Spirit and Opportunity rovers. They believe that the rocks examined by Opportunity were actually formed in water; that those rocks were actually sediments laid down in a shallow salty sea. They've already had outside scientists examine their data and those scientists concur with the conclusions. NASA has a story with explanations and some photos.
That was supposed to be:
/. ate my link
Look harder.
But
Morphing Software
Acidophiles.
There is no environment on Earth too extreme for life, as long as there is liquid water.
Toronto-area transit rider? Rate your ride.
Not usually. Salt deposits on earth generally form inorganically...usually because evaporation in a confined body of water causes it to become supersaturated with respect to Na+ and Cl- ions.
If God had had a computer it would have taken him 7 months to create the earth...if he even bothered to do it at all.
No, salt accumulates in the oceans from the erosion of surface soils and rocks, as the minerals wash into larger bodies of water. This may mean that Mars once had rain.
I want to delete my account but Slashdot doesn't allow it.
You are probably thinking of limestone. Calcium carbonate.
If memory serves, limestone isn't necessarily laid down by critters, but finding stromatolites or chalky cliffs ala Dover would be a very good sign indeed.
As would finding a fossilized opabinia, or one of the cannons the Martians used to launch their cylinders to Earth back in 1898.
Stefan
Well IANAPA (planetary astronomer), but the general consensus is that any water that was there has mostly evaporated and/or frozen. Mars has a very thin atmosphere, and liquid water would not stay put for long -- just as water boils faster at altitude, this is equivalent to water at a very high altitude. Now how water lasted there for thousands of years (or more likely millions, if it has modified the rocks surrounding it seriously), without evaporating is beyond me. I think the current idea is that the atmosphere must have been thicker then. As the atmosphere slowly drifted off (since Mars doesn't have the gravity to hold it), the pressure got less, and the water evaporated too. Sound reasonable?
It (probably) got there in the first place during Mars' formation, and perhaps later due to cometary bombardment.
As to why it was lost, crudely put: evaporation into outer space.
Molecules of volatile gasses, including water vapor, that waft into a planet's upper atmosphere occasionally reach escape velocity and are lost.
Why some gasses and not others? There are a bunch of factors at work:
Heavier gasses -- CO2, for example -- require more energy to get up to escape velocity. They statistically hang around longer.
Larger planets have higher escape velocities.
Planets farther from the Sun recieve less insolation, so there's less of a chance that a molecule will get kicked up to escape velocity.
If you're fast enough you can go view the briefing live, if not its archived on this web page: Briefing
As was said above, salty sea != life bearing sea. It could have been highly acidic (or highly alkaline), and not been able to support life (as we know it anyway).
However, it's a major boon to people looking for evidence of biological process on Mars. Sedementary rocks are by far the best ones for preserving that sort of evidence, as well as forming in the most likely place to find life. If we don't find it there, we probably won't find it elsewhere.
Except they missed the 2/29 deadline.
No shrimp for you!
Frozen carbon dioxide (dry ice).
A print publication has what, a two-three month (minimum) leadtime?
Yow. Usually much longer than that - only the absolutely highest profile papers (like Nobel prize material) get into press that quickly. This might, of course, but they don't have any competition so they can take their time getting the details and analysis exactly right.
Anyway, science by press release usually isn't a good idea, but I'd make some exception for NASA. Even if they get this wrong, the mission has still been a spectacular success, and if they're right, more people will notice now than six months from now when it appears in Science or Nature.
During the news conference the possibility was raised that this water was under a protective layer of ice. So this could have happened without a thick and warm atmopshere.
The huge volcanos make it pretty clear Mars was once geologically active, I think.
The loss of oceans on mars has nothing to do with a loss in mass.
...
The magnetic field Mars current has is not capable of protecting it's atmosphere by deflecting solar wind (the solar wind has been eating away at the Martian atmosphere for some time now; I'm not sure if scientists believe mars ever had a magnetic field capable of doing do, but as it's core has cooled off/solidified the magnetic field on the planet today is what it will always have).
As Mars's atmosphere is stripped away/blown into space, the atmospheric pressure drops. At a certain point, the pressure drops to a point where water cannot exist in liquid form and evaporates -- creating more atmosphere, which then gets stripped away by the solar wind
The cycle continues until all surface water has evaporated or frozen.
No self-respecting skeptic would call an idea foolish when neither that idea nor its converse are substantiated by credible evidence.
Furthermore, no self-respecting skeptic would call anyone foolish while pursuing rational discourse, as it would be nothing more than an ad hominem argument.
This concludes today's lesson on skepticism.
-Peter
Nope. Peer review is a formal process carried out by the journal itself. Each publication has slightly different practices, but the basic process is pretty much consistent. A journal will send copies of your submitted manuscript off to one or more referees--people who are acknowledged to have expertise in the same area. These referees will evaluate whether or not the manuscript is suitable for publication, and possibly suggest changes or additions. For some journals, the referees' identities are concealed from the prospective author.
In some cases, there may be several iterations of review and resubmission before a paper is accepted by the journal for publication. The journal editors have the final say in whether or not the paper is published, but their decision is based heavily on the recommendations of the referees.
Consulting with qualified scientists prior to submitting a manuscript to a journal doesn't count as peer review, but it's certainly a good idea if you reach controversial conclusions or use unusual methods. (Properly, those scientists with whom you consult should be acknowleged in the paper.) In the case of the results NASA has presented here, they have probably had access to virtually all of the most qualified individuals in geology and so forth, so I have little doubt that when these results are published they will have no trouble passing the peer review process. I'm sure that NASA's internal researchers and external collaborators wouldn't be issuing press releases if they didn't believe very strongly that they had a bulletproof conclusion--but technically these data have not been peer reviewed.
~Idarubicin
Big hullabalo a few weeks ago that scientists had shrunk an amino acid detector and analyser to the size of a computer chip. They'll try to get these on the 2009 landers.
Striations can be laid down by wind-blown dust, or by ashfalls from volcanos, to name just two mechanisms tha tdotn require wqter at all. Adn we know that there were volcanoes. If there was an atmosphere at some point, there would have been wind-blown dust. Even in the "wet" category, layers can be created by streams or freshwater lakes. So the 'wet salty' part is also not at all implied by the observation of striated rock alone.
The surface gravity of Mars is 0.38g. Its ability to hold an atmosphere is more closely related to its mass, which is only one ninth that of Earth.
a,e,i,o,u and sometimes w and y (at be if of up cwm by)
NASA has a quite active astrobiology section. And while the geologists involved are not experts, they are just as interested in what could be fossils. In fact, at the planetary science conferences I've been to, the astrobiology talks are some of the best attended. Of course they are being really careful about what they are saying is evidence of life, especially what they are declaring to the general media. Remember the Mars meteorites and those possible fossils? Responsible science requires caution before announcing that every spherical blob is a fossil bacteria. That's why NASA sponsors research projects investigating Earthly bacteria fossils such as the those in the Gunflint Iron formation of Ontario to see what they should look like (check out the work of Rachel Schelble in the scientific journals). Oh, and from guestimating from the crossbedding, the picture in this article is not heavily magnified, these spheres would be awfully big bacteria.
1. What evidence supports or rules out the presence of liquids other than H2O on the surface of Mars, at one time, in large quantities?
No evidence supports any such thing. Nothing rules it out, however, see answer to question #2.
2. How much, if any, of the present evidence could be explained by flows of liquid CO2, nitrogen, methane, ammonia, or some other liquid?
None. The chloride and bromide salts found are soluble in water, not any of those other liquids. By definition, chemical compunds classified as salts require the presence of water.
3. Which evidence, if any, points most strongly to the presence of large amounts of H2O as the liquid in question?
The presence of chloride and bromide salt deposits. They can't be formed any other way, but by precipitation from solution in water. The presence of hematite by itself is less conclusive than that, but in the presence of the salts, it adds to the certainty that water was present.
I know there are currently thought to be large, polar caps of solid H2O, but how much of the current evidence precludes the existence of large seas of some other liquid in the distant geological past?
The salt evidence excludes the other liquids.
Edith Keeler Must Die
Short answer, temperature. It's way, way, way too warm for any liquid like N2 or methane or ammonia to form as a liquid. And it's always been too warm. So the probability that the rock formations occured from any of those liquids is precisely zero.
Secondly, H2O2 is highly unstable, it quickly decomposes into plain-old H2O and O2 in sunlight and/or temperatures above freezing. Both conditions exist and have existed on Mars for billions of years so there is zero probability that H2O2 had anything to do with it.
2. How much, if any, of the present evidence could be explained by flows of liquid CO2, nitrogen, methane, ammonia, or some other liquid?
Zero evidences for all of those substances. Again, its far, far, far too warm. First, carbon dioxide does not exist in liquid form at atmospheric pressure at any temperature. It requires a temperature of 20 degress Celsius and a pressure of 30 atmospheres to form. Mars has never had such conditions so there is again, zero chance liquid CO2 had anything to do with Mars' sedimentary rocks.
The other compounds on your list require extremely cold temperatures to form into liquids. Far, far colder than it EVER gets on Mars for most of them. It also requires a much higher atmospheric pressure than Mars had for most it's existence. Finally, there isn't sufficient quantities of some of these compounds to form rivers, lakes or oceans, nor is there any evidence of that there ever was enough.
Here's the list of temperatures:
- Nitrogen == -196 degrees Celsius @ 1 atmosphere of pressure
- Methane == -162 degrees Celsius @ 1 atmosphere of pressure
- Ammonia == -33 degrees Celsius @ 1 atmosphere of pressure
You answered your own question, the Martian polars caps consist almost entirely of ice. Enough ice that if they were melted they could form seas covering the entire surface of Mars 15 meters deep.It gets cold enough on Mars for this, but there is very, very little amounts of it.
Debunking the "59 Deceits"