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NASA Says Mars Once "Drenched With Water"
NASA is currently holding a press conference (carried live on NASA TV) where they are discussing findings from the Mars rovers. They are saying that the crater that the second rover has landed in has convincing evidence that it was once drenched or covered in liquid water. They cite the tiny spherules, odd holes in the rocks, sulfur in the spectrometric analyses, and evidence of an iron sulfate hydrate (a hydrate is a chemical compound which includes water molecules in the crystal lattice). Update: 03/02 19:45 GMT by M : CNN has a story, or see the NASA press release.
can be found here
-caf
Yes, floats off into space, or turns into ice. There is very little atmosphere, so there is some speculation that the water is in liquid form under the Mars surface somewhere, and it eventually gets pushed up to the surface where it instantly evaporates into water vapor. The thin atmosphere sends this water vapor off into space, or it eventually collects at the two polar ice caps.
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Also, Methionine is an essential amino acid that is not synthesized by the body and must be obtained from food. It is one of the "sulphur-containing" amino acids and is important in many body functions.
It is likely that sulphur, coupled with the different ferrous hydrides can produce viable conditions for life.
The common knowledge was that the ice caps are carbon dioxide ice - dry ice.
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No link in the article. Here is the press release: NASA Press Release
They mentioned that they are going to go check the nearby rock outcropping named "Big Bend" and do basically the same that they did on this rock, in order to see if these rocks were laid down there. I think they're checking exactly that, i.e. whether or not this whole area is laid down with rocks of the same origin (soaked in water), or if they were thrown here by a collision or something.
They said that they weren't sure if the rocks were sedimentary or not. From the sounds of it they aren't, but they did happen to be "soaked in water" or whatever the quote was, allowing the concretions to form in spaces in already existing rock. They haven't found any evidence of layering yet, as far as I know, which would mean sedimentary.
Anybody out there like to comment? Is it a possibility? Could we come back with another rover and get Opportunity working again after it runs out of juice?
Opportunity's batteries will be dead (as in won't charge) inside a year of landing. Since the little guy can't rove without a stored supply of juice, he'll be as good as dead. That's actually one reason why scientists had wanted to use an RTG on the mission. An RTG could have kept it running for years, and in fact would have been one of the LAST components to kick the bucket. Sadly, NASA doesn't want another PR problem like with the Cassini probe.
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Mars has a very weak magnetic field since we speculate that its core has mostly cooled. This means that the planet is poorly protected from harsh solar and cosmic radiation, which is strong enough to break down water into oxygen and hydrogen. These atoms would indeed just float off into space, since the gravatational pull of the planet is not strong enough to retain such light atoms.
That's why I'm not holding out much hope for terraforming Mars. But that doesn't mean we can't still live on it, just in protected chambers on the surface.
The common knowledge was that the ice caps are carbon dioxide ice - dry ice.
This is 5, Informative in a sneaky small print kinda way. Yes, common knowledge was that the caps are carbon dioxide.
Today common knowledge is that the ice caps are a mix of CO_2 and water. In the last couple years, there has been mounting evidence that it is actually mostly water ice, with some CO2.
Google mars polar caps if you don't beleive me.
Posted anonymously 'cause most moderators today wouldn't notice anyways.
It would be highly variable. In a limestone or chert composed entirely of macroscopic or microscopic shells, it would be nearly 100% fossils -- the rock is *made* of biological remains. These deposits can comprise cubic kilometres of rock over vast areas on Earth. In other sedimentary rocks, fossil content would be lower, or almost zero (e.g., wind-deposited sands are pretty poor). Fossil content is highly variable, and depends upon the geological environment at the surface, the age (e.g., Phanerozoic is much richer in fossils than the Precambrian), and biological factors, as well as the scale of the observations (macroscopic versus microscopic). It also depends greatly on the compositions in the original organism -- did it produce a mineral shell, did it have tough organic material that preserves easily (e.g., spores and pollen)? Hell, there are cases where fossils are known from igneous rocks (e.g., trees encased in lava flows) and plenty of metamorphic rocks too (e.g., just about any fossiliferous sedimentary rock can be metamorphosed to a degree before the fossils are destroyed). Bacterial fossils can occur just about anywhere that suitable mineralization is simultaneously occurring, but they can be tricky to distinguish from non-biological processes (even on Earth, where we *know* there is/was life). Some biological molecules are also recognizable ("biomarkers"), even if the body of the organism is not preserved.
So, I don't have a good answer for, but based on intuition, I would guess between 1 to 10% on average for Earth. There are vast areas, however, where you could drive for miles and find 100%, or 0%. Because the distribution is so variable, and we can only speculate on the range of likely environments and rock types on Mars, this would not be much of a guideline.
One thing is for certain, though -- it would take more than a couple of good rovers to eliminate the possibility for Mars.