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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.

56 of 362 comments (clear)

  1. This is HUGE NEWS. by s20451 · · Score: 3, Interesting

    If this is true, and those rocks truly are sedimentary, they should be full of bacterial fossils. All we have to do is get one of them under a microscope to confirm life on Mars.

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    1. Re:This is HUGE NEWS. by FortKnox · · Score: 4, Insightful

      Umm... it depends. Salty sea = Water salt? Or an acidic sea? Water != life. Sea Water != life. Its a posibility, but I think your jumping the gun a bit.

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    2. Re:This is HUGE NEWS. by Scoria · · Score: 5, Insightful

      but I think your jumping the gun a bit.

      Well, you obviously aren't a modern journalist. ;-)

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    3. Re:This is HUGE NEWS. by s20451 · · Score: 4, Informative

      Acidophiles.

      There is no environment on Earth too extreme for life, as long as there is liquid water.

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    4. Re:This is HUGE NEWS. by ShinyBrowncoat · · Score: 3, Interesting

      There's a great science fiction story on the topic of finding fossilized evidence of past life on Mars called "The Carhart Shale", by Grant Callin, which appeared, among other places, in Analog Science Fiction and Fact [v113 #12, October 1993].

      --

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    5. Re:This is HUGE NEWS. by jafac · · Score: 5, Interesting

      Liquid water + Gently flowing means the following:

      Mars was once geologically active -magnetic field protecting from solar radiation - thus, thicker atmosphere, thus, warmer, warm enough for flowing, liquid water, possibly also hot springs or undersea vents.

      I'd be willing to bet that the first sample-return mission will bring back sedimentary rocks filled with fossilized remains of sea creatures. Whether they evolved past the protazoan stage, who knows? But the conditions certainly existed, billions of years ago, as they existed on earth.

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    6. Re:This is HUGE NEWS. by LWATCDR · · Score: 4, Insightful

      "If this is true, and those rocks truly are sedimentary, they should be full of bacterial fossils. "
      Not to be a spoil sport but change "should be full of bacterial fossiles." to "could be full of bacterial fossiles".
      There are a lot of unanswered questions still but all in all very exciting news.

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    7. Re:This is HUGE NEWS. by doconnor · · Score: 4, Informative

      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.

    8. Re:This is HUGE NEWS. by iminplaya · · Score: 3, Insightful

      I'd be willing to bet that the first sample-return mission will bring back sedimentary rocks...

      I hope they don't do that. It would be a tremendous waste of resources. This is one case of many where it is much wiser to send the equipment up there to do the analyzing. Kind of like what we're already doing.

      --
      What?
  2. A Salty Sea on Mars by Captain+Tenille · · Score: 5, Funny

    Well, I suppose that would explain the ruins of a Long John Silver's that Viking 2 found in the 70s.

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    1. Re:A Salty Sea on Mars by beacher · · Score: 3, Funny

      Speaking of Long John Silver's... HEY FREE SHRIMP!

    2. Re:A Salty Sea on Mars by semifamous · · Score: 4, Informative

      Except they missed the 2/29 deadline.

      No shrimp for you!

  3. Single cell organisms to follow... by paleobones · · Score: 4, Interesting

    I bet they'll soon find some stuff that will look like biological processes. Cool stuff...

  4. Ok by Burgundy+Advocate · · Score: 5, Insightful

    It's time to get our asses to Mars. There is far too much to learn for us to just sit around and do nothing.

    Especially considering some of this may be applicable to what will happen to our own planet in the future. We currently have seas. Mars used to. It'd be a good idea to figure out why they don't have them anymore.

    --
    Dragging people kicking and screaming into reality since 1996.
    1. Re:Ok by Dysan2k · · Score: 4, Funny

      Easy... the colonists revolted and the Go'auld decimated the planet.

      --
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    2. Re:Ok by steelerguy · · Score: 5, Insightful

      Although I agree with you, it would be a dangerous mission. Look at the outrage the explosion of the latest space shuttle caused. Although there would be plenty of astronauts willing to take the risk, my guess is that, no time soon, will they even be given the opportunity.

      It seems that most people have forgotten that this kind of exploration can be dangerous. I think people would be leary of sending Lewis and Clark out in this day...but what if they get sick...what if Clark falls..yadda yadda

    3. Re:Ok by Iron+Sun · · Score: 5, Insightful

      Scientists think they have a handle on why. Low atmospheric pressure means that water can't exist in liquid form on the surface any more. Mars' atmosphere was denser billions of years ago during what is called its Noachian period. For various possible reasons (such as a lack of a magnetic field to protect against the stripping solar wind) Mars' atmosphere was mostly lost, and all the water boiled off into vapour, and was either lost to space or deposited in the ice caps.

      A lengthy and detailed overview of current theories can be found here: Part 1, Part 2. Especially cool is the stuff about Mars' "obliquity cycles", namely the fact that the planet's axial tilt appears to be chaotic, and may have been completely tipped over on its side several times in the past. During such a period Mars would not have ice caps at the poles, but rather an ice belt around its equator.

    4. Re:Ok by myowntrueself · · Score: 4, Interesting

      Yeah exploration is *far* too dangerous to risk the lives of American astronauts.

      American astronauts should sit at desks pushing their mouse around playing solitaire or somthing.

      I really pity them... its sad that such cowardice should infect such a (formerly) great nation.

      Yeah *troll*, *flamebait*, *whatever* but its true.

      --
      In the free world the media isn't government run; the government is media run.
    5. Re:Ok by steelerguy · · Score: 3, Insightful

      The sad thing is the astornauts themselves are not the one's complaining. They seem to understand the risks and are willing to take them.

      Making this an anti-American argument was just silly though. In fact, we are much more likely to send people into space than any other country. That is why we have/had so many hitch hikers on the space shuttle missions.

    6. Re:Ok by johnjay · · Score: 4, Insightful

      On the face of it, it is an inconsistant national philosophy that American soldiers are regularly expected to risk their lives, but space flights are held to a standard of 100% success. America is supposed to be a nation of cowboys. The "cowboy" image is much closer to that of an explorer than a soldier.

      I think it's because space science is held to a perverted form of perfection, rather than because Americans as a people have become cowards. Every time an astronaut dies, the space program is shut down and there is an intense investigation. Inevitably, something is found that could have been done differently/better and prevented the accident. NASA is criticized and expected from then on to make no errors. It is an admirable goal, and has produced some amazing machines and science, but it stifles progress.

      When space travel is so commonplace that it is no longer news, the astronauts will be allowed to take risks. But, until then, the engineers and scientists involved in space will be more concerned with not being the subject of one of those witch-hunts, rather than actually doing something. I am not criticizing the scientists of NASA; I think they are held to unrealistic expectations.

  5. A Salty Sea? by bcolflesh · · Score: 3, Funny

    Sure, sure - next they'll try to make us swallow Martian seamen!

  6. Peer Review? by TrebleJunkie · · Score: 4, Insightful

    Okay, so they've shown it to a few scientists who concur.

    Whatever happened to *publishing* the results of your experiments (and the data) in peer-reviewed journals?

    Now, granted, there's plenty of political bias in the journals -- anyone that thinks science is purely dealing with the facts these days is *beyond* an idiot, but still. Just because you've got the rovers and you've got a daily press conference doesn't mean that your statements should be treated as anything but sensational speculation this early on.

    If NASA were claiming Cold Fusion or Perpetual Motion, they've be laughed out of the scientific community for broadcasting just a revolutionary claim without first publishing.

    --

    Ed R.Zahurak

    You know, oblivion keeps looking better every day.

    1. Re:Peer Review? by Daniel_Staal · · Score: 3, Insightful

      A print publication has what, a two-three month (minimum) leadtime? I'm sure it'll get published as soon as possible. The article is probably already submitted.

      In the meantime they've had an independent review, and put out the news as quickly as possible. A reasonable compromise.

      --
      'Sensible' is a curse word.
    2. Re:Peer Review? by rabel · · Score: 4, Interesting

      Dude, this stuff is happening Live, as you see it. The fact that they've had time to let other scientists peer review their work, even at the highest levels, is pretty cool. There will be plenty of peer review going on over the next many years, but for now I think the Mars Rover science teams are going out of their way to make sure they are only reporting what they believe they can prove. None of them has stated that there was life on mars, they're just reporting the facts as they see them.

      I'll bet you they'd be willing to debate the facts with you if you had credentials to match your statements above.

      For now, this is a pretty big deal and one step towards making us wonder seriously if there was life on mars.

    3. Re:Peer Review? by kippy · · Score: 4, Interesting

      I don't think NASA is claiming anything more than broad speculation with lots of caveats. They're pretty sure there was lots of water. When? How much? How long? Who knows. Since I'm paying for this info anyway, I'm glad they're making it available as quick as they are.

      Besides, isn't releasing this data to the world defacto peer review?

    4. Re:Peer Review? by tfreport · · Score: 5, Interesting

      Exactly. NASA could have sent it to a journal that would have a handful of scientists look at the arguments (which they are sure to do) or they could let the world know what they were up to and in the process have the entire world analyze things. Sure this data is through a filter of the press, which may make it harder for scientists everywhere to analyze the claim. But they did do it live on NASA TV and surely have information on their website (or soon to). Therefore for you scientists out there, you will have a great opportunity to analyze, scrutinize, etc. a huge finding.

      Meanwhile, Joe Blows like me can actually hear about it and read about it rather quickly, instead of waiting for the filter down process after a peer-reviewed journal down to a general science magazine down to Newsweek or Slashdot. And I am very happy about that. After all, I have at least a couple pennies invested in those two rovers. And I should have a right to know what they have found.

    5. Re:Peer Review? by the+gnat · · Score: 3, Informative

      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.

  7. Salty sea? by JordanH · · Score: 3, Insightful

    I don't know anything about this area, really, but in seas on the earth isn't it thought that salt accumulation occurs from activities of living (and dying) organisms?

    1. Re:Salty sea? by Gothmolly · · Score: 5, Informative

      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.

      --
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  8. Next headline you'll see by Tebriel · · Score: 4, Funny

    "Opportunity Rover on Strike: Demands Pina Coladas, Sunscreen, and 5 days off to enjoy time at beach."

    --
    The Blaster Master Fighting for Truth, Justice, and Evil Pie since 1979
  9. Re:makes sense by steelerguy · · Score: 4, Funny

    Im so glad all these scientists have finally be able to validate your claim...you must be very proud.

    Suddenly I'm hungery for a nice juicy steak...

  10. Re:Mars Play-by-play by 0x0d0a · · Score: 5, Insightful

    Oh, for chrissake.

    They're throwing out updates as soon as they get them because, really, this is so far beyond anyone's expectations that we're really floored.

    The big deal is that if we really do find life that evolved separately from terran life, it throws a *huge* quandary for some philosophies and a lot of world religion, besides being a major psychological breakthrough for science. And the signs look *awfully* good.

    Besides, NASA had a lot of bad press from Columbia, and they're hungry to be able to give good news.

    And, really, aren't you even a little bit excited.

  11. Best thing since first grade! by Milo+Fungus · · Score: 4, Interesting

    I remember back in Kindergarten when all of my classmates and I wanted to be astronauts when we grew up. All of our dreams were dashed to bits the next year when the Challenger exploded. We all went back to wanting to be fire fighters or whatever.

    I tell you, these Mars rovers have done more to get me excited about space exploration than anything which has happened since then. I'm currently applying to medical school, but a long-dormant part of the back of my mind whispers, "You should have been an astronaut after all!"

    What an amazing day to live in, when we may be at the threshold of discovering LIFE on ANOTHER PLANET!

    1. Re:Best thing since first grade! by rabel · · Score: 3, Insightful

      Actually, if you were deterred from being an astronaut because of Challenger, then it's probably for the best. No offense, but to be an astronaut you gotta have some huge nuts (so to speak) to ride those flying bombs up to orbit.

      What a great job, but you know... it's probably full of meetings and paperwork and boring-ass busy work most of the time, just like all the rest of us.

    2. Re:Best thing since first grade! by JavaLord · · Score: 3, Funny

      I'd hate to break this to you but...not everyone gets to be an astronaut when they grow up

  12. Until recently no one believed water was there! by purduephotog · · Score: 4, Insightful

    You can't blame the guy for being excited. Skeptics called everyone 'foolish' for believe that water could have existed in any significant quantities on mars, in any form.

    He may be jumping the gun a bit, but those water seekers certainly scored big by hitting two targets that both were drenched in water at one time.

    'Course, nothing drives people better than proving someone else wrong...

  13. What a discovery!! by DR+SoB · · Score: 4, Funny

    I can't believe they actually discovered they have rovers over there:

    "NASA has made another announcement, live on NASA TV, regarding the discoveries of the Spirit and Opportunity rovers. "

    --
    Mod +5 Drunk
  14. Re:Crap first post chance and I have nothing to sa by Anonymous Coward · · Score: 3, Funny

    Almost makes you wonder if buying that low UID on eBay was even worth it, huh?

  15. Surf's up on Mars! by HarveyBirdman · · Score: 5, Funny
    "It must have been radical," said NASA spokesdude Jeff 'Sex Wax' Corona at a press conference held in a salt water taffy booth in Atlantic City, New Jersey. "The waves would have come in out of the north, and based on our topographic mapping, would have curled perfectly and just tubed out for miles."

    "Would there have been life there?" asked Jayson Blair, new cub reporter for Tool & Die Quarterly.

    "Dude!" said Corona, "With wave action like that how could there not be life? Can't you just imagine the green-skinned Mars babes lounging around, sipping Martain pina colodas while rubbing tanning butter all over their Barsooms."

    "So you think Mars mught have supported intelligent life?" asked Baba O'Reilly, a distant cousin of Bill O'Reilly working for Akron City College Daily Herald, Mid-Morning Edition.

    "Yeah... yeah... those barsooms, man," said Corona. "Huh? What? Oh, well, you wouldn't want them to be too intelligent, you know what I mean, man?"

    The press conference was brough to an early end when a catsuited Gloria Allred and Camille Paglia paraglided into the taffy booth and beat Corona into submission.

    --
    --- Ban humanity.
  16. Re:NASA's "Major" announcements by Hoi+Polloi · · Score: 3, Interesting

    Salt water is important news because it shows that the water was there for a long period of time and that it had some sort of feeds (rivers?) to keep adding eroded minerals and maintain water levels, not just some brief puddle.

    --
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  17. Low Gravity, for one Re:makes sense by StefanJ · · Score: 5, Informative

    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.

  18. Re:Mars Play-by-play by jsebrech · · Score: 4, Insightful

    if we really do find life that evolved separately from terran life, it throws a *huge* quandary for some philosophies and a lot of world religion

    Like when they first showed the earth wasn't flat, and suddenly christianity collapsed because a flat world was one of its cornerstones? Don't kid yourself, there is a world of difference between dogma and religion. Dogma comes and goes like the tides, religion is eternal. The handy thing about holy scripture is that you need to interpret it, so what it actually says is left up to the interpreter. When we do find conclusive evidence for alien life, the major religions will all come back and say "well ofcourse, our holy scripture said it all along, here's the passage that mentions it."

  19. Shai-halud! by Ececheira · · Score: 3, Funny

    So, Mars had a Sea and now it's dry and desert-like...

    How long until they find worm-sign?

  20. Luck? Or lots of water? by sampson7 · · Score: 5, Insightful

    What amazes me isn't so much that they discovered evidence of water on Mars, it's that they've discovered so much of it so quickly!

    This is really the first fully sucessful mission to Mars whose primary function is to search the geologic record for evidence of water -- and not only did they find it -- they found it twice and quickly at that!

    First of all -- kudos to the mission planning team. They picked their landing spots beautifully (and then hit a moving target from a moving target -- this isn't Lawn Darts folks. That alone is impressive.)

    Second -- how much like Earth is Mars??? If the entire planet was covered with Oceans at one point, then (obviously) finding water isn't that remarkable. If, however, Mars is geologically similar to Earth, then 3/4 of the "land" would have been covered with water at one point. But I don't see that.

    Mars seems to have little/no active tectonics -- and therefore no sea floor spreading. Also, since we can't find magenetically charged banding on the ancient Mars "ocean" floor, it suggests to me that Mars simply does have the characteristics that created large oceans like Earth does.

    What I want to know is if the rovers are cabale of taking a thin-section of some of these sedimentary rocks. So much of the ocean floor on our planet is actually microscopic bits of dead diatoms and other creatures -- that would certainly answer the life question!

    Which brings me back to point 1 -- if there isn't that much water, those rocket scientists really did their homework.

    Wow. This is some seriously cool sh*t.

  21. Why search for fossils? by Aggrajag · · Score: 4, Interesting

    What if there's still some form of archbacteria living on Mars? I mean the ones living on earth can survive basically anywhere. Or they could be hibernating as the bacteria on earth are able to do.

  22. Re:What they'd find by tijnbraun · · Score: 4, Insightful

    If bacterial fossils would be found, it could possibly tell us a lot about how life orginated on earth.

    The biggest problem with all the hypothesis of the origin of life is that of falsification. This problem is not confined to theories of the genesis of life alone.

    All biologist that want to explain why a certain animal evolved from its ancestors in such a way and not in an other way, have this problem. So do historians. "What would have happened if king George the whatever died at 18 of pneumonia, I assume that germany bla bla ".

    You can probably tell a nice story, but do you have any data to prove your assumptions?. Although biologist often are in a better position to prove their assumptions (there are a lot more animals with the same niches/ancestors, living in different continents/islands evolving in different species in comparison to king George's), it often resorts to just story-telling.

    If life did orginate independently on Mars and any remains of this event could be found and studied, it could not only falsify a lot of hyphotesis but also stir new ones in the right direction

  23. Re:any theories by Keeper · · Score: 4, Informative

    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.

  24. What IS that?! by rchoetzlein · · Score: 3, Interesting

    What I'd like to know is, what is that clearly visible, dark, yet shiny object in the foreground in the Meridiani Planium image at 97 degs (the largest image download has azimuth degree marks)?

    It can't be the Backshell & Parachute which are at 235 degs. It can't be heat shield either, which is much farther away. And from the image, it clearly is much darker and rises above the surface.

    Also interesting is the fact that it lies on one of the bounce marks from the airbags, but none of the other bounce marks have this feature. Its' in line with the distant East Crater (probably by chance), but clearly in the foreground...

  25. Re: Article pointed to is dated... by Ralph+Spoilsport · · Score: 4, Interesting
    and it contains this little arrogant gem:

    What we DO know now with reasonable certainty is that such water could not possibly have been any warmer than near-freezing. Noachian Mars may have been "cold and damp", but we can now rule out the view of some hopeful scientists that it must have been "warm and wet".

    Well so much for reasonable certainty, eh?

    AN interesting question those articles do pose, though, is - if Mars was so wet for so long (wet enough to make this sedimentary rock) why is there so much Olivine up there? Olivine breaks down when exposed to water - even frozen water.

    It's a mystery - so I guess we'll just have to pack up the truck and go check it out.

    Swimmin' pools, movie stars...

    RS

    --
    Shoes for Industry. Shoes for the Dead.
  26. Re:Mars Play-by-play by phyy-nx · · Score: 3, Insightful
    Like, say, this LDS scripture:

    "And worlds without number have I created; and I also created them for mine own purpose;... But only an account of this earth, and the inhabitants thereof, give I unto you. For behold, there are many worlds that have passed away by the word of my power. And there are many that now stand, and innumerable are they unto man; but all things are numbered unto me, for they are mine and I know them."

  27. Not being a smartarse but... by niittyniemi · · Score: 3, Insightful



    Wouldn't a geologist (I'm not but I did) conclude that earlier pictures showed clear signs of the rocks being sedimentary?

    Look at the area below Zugspitze in the picture above and then try and tell me with a straightface that those striated rocks are igneous in origin.

    The question is why did they wait so long to announce the fact that there were sedimentary rocks?

    Maybe a geologist could tell me whether there are any igneous rock formations that might look sedimentary & they therefore had to do further analysis.

    --
    The Machine stops.
  28. Liquid != H2O by F00F · · Score: 4, Interesting

    I've read a lot of discussions lately about recent evidence for why there must, at one time, have been liquid water on Mars. But, much of that evidence relates to the deposition of sediment, presence of erosion patterns, aftereffects of evaporation, presence of salts, crystallization patterns, and so forth -- none of which (to my knowledge) requiring the liquid in question to be H2O. Some of the evidence, on the other hand, relates to the formation of minerals such as hematite, which presumably form only in or near liquid H2O, and not, say, liquid H2O2, liquid CO2, or liquid N2. The biggest question(s) I have that I've not seen well addressed are:

    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?

    2. How much, if any, of the present evidence could be explained by flows of liquid CO2, nitrogen, methane, ammonia, or some other liquid?

    3. Which evidence, if any, points most strongly to the presence of large amounts of H2O as the liquid in question? 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?

    I apologize if these questions are simple or completely baseless. I am not a geologist, and am legitimately curious.

    Cheers,

    F00F
    1. Re:Liquid != H2O by kindbud · · Score: 4, Informative

      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
    2. Re:Liquid != H2O by DrMorpheus · · Score: 3, Informative
      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?

      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
        It gets cold enough on Mars for this, but there is very, very little amounts of it.

      Which evidence, if any, points most strongly to the presence of large amounts of H2O as the liquid in question? 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?
      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.
      --
      Debunking the "59 Deceits"
  29. Striated rocks are not necessarily sedimentary by Intraloper · · Score: 3, Informative

    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.

  30. My Mozilla Tabs say... by rat7307 · · Score: 4, Funny

    OT: but I had to share it:
    My current titles on my tabs in Mozilla say:

    "NASA Finds Critical Ass...."

    and

    "NASA Says Mars Rocks..."

    Kinda funny...

    --
    Burma?