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Space Science

Hellish Vision of Mars Unveiled 144

Posted by CowboyNeal from the fire-in-the-sky dept.
mvladivostok writes "Yahoo has an interesting little article in which it is suggested that Mars may not have once been a warm, wet and hospitable planet that somehow lost its atmosphere; instead, it is suggested that the dead planet was occasionally bombarded by melting meteorites that carved out its distinctive craters and valleys. An interesting read."
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Hellish Vision of Mars Unveiled More

Hellish Vision of Mars Unveiled

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  • Still (Score:5, Interesting)

    by Thaelon ( 250687 ) on Friday December 06, 2002 @09:16AM (#4825992)
    It's got water, that would make future colonization that much easier/more feasible.

    • Re:Still (Score:1, Funny)

      by Anonymous Coward
      Yeah... But there goes our "We're just making it how it used to be!" argument when foolish Greenies are protesting our tereformation of the planet.

      • Re:Still (Score:4, Funny)

        by Jace of Fuse! ( 72042 ) on Friday December 06, 2002 @09:27AM (#4826046) Homepage
        Greenies want to keep the earth from changing.

        Would you call people who want to keep Mars from changing either Reddies or Brownies?

        • Re:Still (Score:4, Informative)

          by lovebyte ( 81275 ) <lovebyte2000@gm[ ].com ['ail' in gap]> on Friday December 06, 2002 @09:43AM (#4826110) Homepage
          I am reading the 3rd volume of the excellent Mars trilogy of Kim Stanley Robinson: Red Mars, Green Mars and Blue Mars. In the story, those that are for the terraforming of Mars are the Greens and those against are the Reds.

        • Re:Still (Score:1, Troll)

          by drinkypoo ( 153816 )
          I vote for "assholes". Still, not as bad as the people who want to keep the moon pristine. Let's see, airless ball of rock and dust with no chance of any living thing... Let's maintain it in its pristine state!

          Of course, in order to do that, you would have to institute an asteroid point defense system...

        • Re:Still (Score:3, Funny)

          by zephc ( 225327 )
          well, since the cause of the coloring on mars is Iron Oxide, I think they should be called Rusty

          *ba dum!*
          • And there ya go. Plenty of water and iron. Wonder if we were to seed some cyanobacteria and simple plants would Mars then be more hospitable.

            Seems a great place to build the Vogon fleet. But I guess that's highly improbable.
        • : Would you call people who want to keep Mars from changing either Reddies or Brownies?

          Oranges.:)
  • We should send a team of Disney lawyers to check it out in person.
    • We should send a team of Disney lawyers to check it out in person.

      Whereupon they'll be sent packing back to Earth by Warner Bros. representative Marvin the Martian. :)
    • Naw, they'll just say, 'Red planet? Doesn't look Red to us! It's a perfectly normal color!' and then the anime fans will be all up in arms again. ;)
    • That's about the worst thing we can do. No nation may claim parts of mars, but a corporation might try. Do you want the first thing that the immigrants to Mars see on arrival to be a giant mickey face on the surface?

  • What? Not Doom 3? (Score:5, Funny)

    by dzym ( 544085 ) on Friday December 06, 2002 @09:18AM (#4826001) Homepage Journal
    At first I thought this article was about Doom 3.

  • Life on Mars? (Score:4, Interesting)

    by Man Eating Duck ( 534479 ) on Friday December 06, 2002 @09:19AM (#4826009)

    From the article:
    "Only during the brief years or decades after the impact events would Mars have been temperate, and only then might it have bloomed with life as we know it," they wrote.


    If earth is anything to go by, I thought evolution of self-reproducing organisms would require quite a few million years and a primordial soup...

    • Re:Life on Mars? (Score:2, Interesting)

      by saider ( 177166 )
      There may have been primitive bacteria or algae that were transported to Mars from Earth. These organisms would then lay dormant, waiting for the right conditions to bloom. When the event was over, the organisms would revert to a dormant state to await the next catastrophe/windfall.

      There has been a bit of discussion about this "interplanetary cross-pollination" lately. I'm to lazy to look for links, although there have been several slashdot topics posted.

      • Re:Life on Mars? (Score:3, Insightful)

        by foistboinder ( 99286 )
        There may have been primitive bacteria or algae that were transported to Mars from Earth.

        True, but it's more likely to have happened the other way (assuming there was life on Mars). "interplanetary cross-pollination" from a small planet to a large planet is easier than the other way around. The escape velocity for the smaller planet is lower and the gravity well of the larger planet make it easier for the debris to "find".

        • Ah! Good point.

          But would the likelihood not go back to favor Earth -> Mars because a rock from earth is much more likely to have life on it? Fewer rocks are ejected, but they have a much higher chance of harboring life. As opposed to more rocks that are mostly dead.

          All of this is more or less a numbers game, like the Drake equation. I say we smash some large objects into the Earth and Mars and get some measurements.

          • But would the likelihood not go back to favor Earth -> Mars because a rock from earth is much more likely to have life on it?

            Probably, but if the conditions for life on earth and Mars were equally favorable when the solar system was younger, then it shifts to Mars.

        • Not only that, it's more likely to go from an outer planet to an inner planet, due to the gravity well of the sun.

    • Re:Life on Mars? (Score:3, Insightful)

      by error0x100 ( 516413 )

      If earth is anything to go by

      Why do people always want to assume that Earth is 'something to go by', i.e. that Earth is probably "representative of an average planet with life"? Its the only planet with life on that we know have, making it a sample of size 1, and as such we have absolutely no clue whatsoever where it would lie on any statistical curves. Earth could just as well be a statistical outlier in most things, for all we know. Making any assumptions about other planets, based on Earth, seems like a dicy process to me. Perhaps Earth has been really slow on the evolution scale, i.e. perhaps other planets required much less time for evolution to progress. Or it could be the other way round, perhaps it was really quick. Or perhaps it was just average. Or perhaps in other parts of the universe, other factors play bigger roles, such as 'seeding' of planets. Collectively, we don't yet have enough scientific knowledge and understanding of these processes to even begin to make proper "educated guesses".

      Just because Earth is the only planet we've seen, does not mean we can make statistical assumptions about it. Nor can we extend such assumptions to other planets, such as Mars, because for all we know, Mars may also have been a statistical outlier.

  • like earth? (Score:4, Insightful)

    by mr100percent ( 57156 ) on Friday December 06, 2002 @09:19AM (#4826012) Homepage Journal
    "instead, it is suggested that the dead planet was occasionally bombarded by melting meteorites that carved out its distinctive craters and valleys"

    Wait a minute, isn't that the same as earth and the rest of the planets? I mean, mercury doesn't get this kind of attention.

    • Re:like earth? (Score:2, Informative)

      by The Only Druid ( 587299 )
      "Wait a minute, isn't that the same as earth and the rest of the planets? I mean, mercury doesn't get this kind of attention."

      No, what they're saying is this: Earth has two basic kinds of geo-physical features, those caused by extraterrestrial effects such as meteor impacts, and those caused by terrestrial effects such as techtonic plate shifting or magma bursts as lava through volcanos.

      The point here is that mainstream thought suggests that the craters/valleys were caused by water pooling/travel akin to that of earth, whereas this new model suggests that the craters/valleys were exclusively caused by the impacts. In such a system, you explain why the tributaries that are normally associated with water bodies aren't present on mars, along with several other problems.

    • Re:like earth? (Score:4, Funny)

      by iomud ( 241310 ) on Friday December 06, 2002 @10:22AM (#4826316) Homepage Journal
      It's battered planet syndrome.
    • "In contrast, we envision a cold and dry planet, an almost endless winter broken by episodes of scalding rains followed by flash floods."

      Well, *I* envision the god of speed, running through the skies at night.

  • A bit contrived, perhaps? (Score:5, Interesting)

    by Montreal Geek ( 620791 ) <marc@u b e r b ox.org> on Friday December 06, 2002 @09:22AM (#4826023) Homepage Journal
    This is certainly not my field (more like a hobby) but it it just me or is this scenario a bit contrived?

    While it's certainly possible that Mars would have been bombarded this way, it doesn't appear likely for two reasons:

    For one, there is no evidence of any other planetary body which would have gotten a significant infusion of water this way and it seems unlikely that Mars would have been the only target.

    But the most important detail seems to be to just be a question of quantity. Regardless of maturity, in order for deep riverbeds such as appear on Mars to form you need a lot of water flowing for a fairly long time (years, not days). To get that water from impacts would mean that a LOT of such impacts need to have taken place over a (cosmologically) short period; which makes the first point above all the more noticable.

    Even if Mars did get significant amounts of water this way (or had enough of it melted out by side effects) the water wouldn't have been around long enough to make geological constructs unless there was an atmosphere allowing it to remain liquid long enough to flow around for years.

    I'm surprised someone at NASA would publish national-enquirer quality science like that. More likely, Yahoo misread the paper to extract the nice sounding bits.

    -- MG

    • Re:A bit contrived, perhaps? (Score:5, Informative)

      by franimal ( 157291 ) on Friday December 06, 2002 @09:43AM (#4826112) Homepage
      Nope! One theory goes that this is the same way that Earth got its water. (Orginal water was boiled away in early hot days when there was no atmosphere). The only problem with such theories is the isotope ratios of the water found in comets versus Earth. Search around a bit, you'll find more. One [spaceflightnow.com] Two [scienceweek.com] Three [nasa.gov]

    • Re:A bit contrived, perhaps? (Score:5, Informative)

      by ianscot ( 591483 ) on Friday December 06, 2002 @09:44AM (#4826123)
      For one, there is no evidence of any other planetary body which would have gotten a significant infusion of water this way and it seems unlikely that Mars would have been the only target.

      Discover ran a story about someone who thinks Earth is still being bombarded by smaller bodies like this -- it was a couple of years ago I think. He's regarded as a flake, but he's at least on the edges of the real scientific community.

      Regardless of maturity, in order for deep riverbeds such as appear on Mars to form you need a lot of water flowing for a fairly long time (years, not days).

      Ever hear of the Lake Missoula ice-age floods? Water from a penned-in glacial lake burst through ice dams several times, ripping up the northwestern US in colossal floods. The entire surface of eastern Washington state was formed through quite sudden flooding [opb.org]:

      "In about two days the water of Glacial Lake Missoula emptied through the breached dam. The amount of escaping water was equal to ten times the discharge of all the Earth's rivers today." Water several hundred feet deep flooded the region and ripped up hundreds of feet of soil and rock, carrying it inside the torrent of water westward toward the sea. The flood cut channels and carved islands, leaving behind the scarred landscape now called the Channeled Scabland.

      Imagine ripples like in a streambed, only on the scale of hillsides. It doesn't necessarily take years.

      Not that I'm buying this idea, but it's not as outrageous as all that.

      • Yes, but notice that we have an atmosphere which allows water to remain wet. So while I presume that this is somewhat plausible, the explanation does seem fairly improbable.

        Consider for a momment that ice did impact and formed a large crator. Is it now hot enough to melt? I thought it was more likely that it would of turned to a vapor (atmosphere required again right?). Even if it does melt into water, where is it going to go? It's in a crator. It's got no where to run off too. Even if it did, it would be a race for it to run off versus the cooling action of space. Skip ahead a little bit. Now, we should see a crator with vast amounts of ice. Even it hadn't frozen completely at the time, surely the top would freeze quickly enough (like a frozen lake) to prevent it from running off somewhere.

        After it's all said and done, I can't believe that such a thing was very probable. As such, seems much more likely that Mars had an atmosphere with rivers and some event happened which destroyed it (huge chunk of ice anyone? ;).

        • A big enough impact can easily impart enough energy to warm the surrounding area for a few hundred years, particularly if it fractured the crust and allowed a significant magma eruption to occur.

          Objects with the kind of mass the article is talking about are relatively rare now, but it is thought that they were abundant in hte early solar system. Over the billions of years, the planets have kind of swept up most of the debris that crosses their orbits. Nature likes a tidy orbital plane.

          • That was my point...partially anyways. That is, if you have that kind of serious heat and energy, I'm not sure water is going to be flowing. Rather, I'd be expecting it to be burning off. And if it's in a crator that's deep enough to hold it while it melts, where is it going to be flowing to. After all, once the ice melts, the remaining water will more easily fit into the crator than the ice did.

            See what I saying?
            • We are talking climate change that might affect an entire hemisphere of the planet here. No crater's going to be that big. Mars does have significant gravity and holds a decent, if a little thin atmosphere. We are talking about events that take a few hundred years to complete. An eyeblink in geologic time, but not as quick as ten minutes after the impact.

              If a bolide impact at the end of the Cretaceous can so alter the Earth's climate for long enough to drive an entire order to extinction (Dinosauria), then a similar impact on Mars could certainly give it liquid water for a few decades.

    • Re:A bit contrived, perhaps? (Score:1)

      by Anonymous Coward
      For one, there is no evidence of any other planetary body which would have gotten a significant infusion of water this way and it seems unlikely that Mars would have been the only target.


      A snowball the size of Earth wouldn't have any perceptible affect on a gas giant the size of Jupiter. Saturn and Uranus could also be hit by large asteroids without leaving marks. We can't really see Venus to know if it's been hit.

      Regardless of maturity, in order for deep riverbeds such as appear on Mars to form you need a lot of water flowing for a fairly long time (years, not days).


      That's where you're wrong, or at least speculating wildly.

    • From the article: "The impacts would have injected steam into the atmosphere, both melted from the surface and from the asteroids and meteors themselves. This would have rained onto the surface "at a rate of about 2 meters (six feet) per year," they wrote."

      Also from the article: "Only during the brief years or decades after the impact events would Mars have been temperate..."

      So they are saying that approximately 2 meters of rain fell per years for a period of ranging from years or decades. That sounds like "a lot of water flowing for a fairly long time (years, not days)."
    • Actually you can get major canyon systems formed in a period of few days following a major flood - there's a canyon in Iceland that runs from Vatnajokull glacier in the south to the north coast, which was largely formed from a single jokulhaup (very large flood from beneath the glacier). Such jokulhaups are caused by vulcanism beneath glaciers - and the exact same mechanism has been suggested for the origin of Martian canyons.

      Mars was tectonically active until relatively recently (perhaps less than 100 million years ago). Yet the article talks about impacts 3.5 billion years ago, continuing for less tha 0.5 billion years. Why have these not been obliterated by the more recent tectonics? And as I recall some of the canyons have eroded much more recent small impact craters, suggesting that free water has flowed much more recently.

      Note also that 3.5. billion years ago is close to the formation of the planets. Planets form by the accretion of many such impacts, so this *is* a good explanation of how mars aquired it's water (and indeed all of it's mass).

      But it is unlikely to account for subsequent melting and flow of that water, which is more likely to be due to 'weather' system (which implies an atmosphere), or subsequent melting by volcanic activity. The mechanism described in the article ceases c. 3 billion years ago, yet 'water-based' errosion processes have been occuring much more recently.

    • Re:A bit contrived, perhaps? (Score:2, Insightful)

      by Anonymous Coward
      I was pretty sure the reason why Mars lost it's atmosphere was because it's core lost it's coherency and it's magnetosphere became weak enough for the solar wind to slowly strip it away.

    • >For one, there is no evidence of any other planetary body
      >which would have gotten a significant infusion of water
      >this way and it seems unlikely that Mars would have been the
      >only target.

      You must not have read the article, or at least you didn't read it carefully. The water wasn't all delivered by the bodies that collided with Mars - much of it would have already been in place, trapped as ice beneath the surface and at the poles (as we believe it is today). Furthermore, we have lots of evidence that water ice can be delivered to planets via comets - we actually watched comet Shoemaker-Levy 9 smash into Jupiter in 1994. That comet consisted of around 21 fragments, some with diameters of well over a mile, and had a visible impact even on that giant planet's atmosphere. You can visit this site [tamu.edu] to get an overview of the massive (and unexpected) results of their fiery plunge into Jupiter. Had it smacked Mars instead, it would have injected a vast amount of water vapor (and other gasses) into the thin Martian atmosphere, radically altering its composition.

      Even today, if a large comet or even a sufficiently sized iceless asteroid slammed into the surface, it would produce a massive explosion, throw mountains worth of material into the atmosphere and generate a tremendous shockwave. The heat that would result from such events - including the rain of ejected rock falling back to the surface of Mars - could melt that subsurface permafrost on a global scale. Throw in any ice delivered by the impactor itself (for example, from a 20 mile wide comet) and you'd have one hell of a flood.

      As CO2 and water vapor poured into the atmosphere, they'd rapidly insulate the planet, allowing still more ice to melt and resulting in colossal floods on a global scale. Another article I've seen on this theory points out the atmosphere could become hotter than a self-cleaning oven (more than 800 degrees Fahrenheit). This flooding could go on for years, until Mars cooled and its water vapor / CO2 atmosphere largely precipitated out, seeped through all the regolith at the surface, and refroze as a layer of permafrost.
  • i suddenly can't believe in total recall anymore. the oxygen machine could not have withstood the meteor bombardment...

    • Before the bombardement there was no water on Mars, so the O2 factory was of no use.
      The aliens must have built it after the bombardment!

  • Hmm... Reminds me of the vision of Mars in _Red Mars_ by Robinson.

  • 3.85 billion years ago ... (Score:5, Interesting)

    by franimal ( 157291 ) on Friday December 06, 2002 @09:26AM (#4826040) Homepage
    The same thing was happening on Earth. Earth gets smacked [newsfactor.com], life gets crushed, picks itself up, and tries again. Thankfully, life has yet to crush itself.

  • speculating (Score:3, Insightful)

    by katalyst ( 618126 ) on Friday December 06, 2002 @09:29AM (#4826056) Homepage
    Mars has always been a mystery to us humans, right from H.G.Well's War of the world , to the recent Red Planet, we've been fantasizing about Mars. The Pathfinder has been the most exciting Mars project yet !!! It's interesting to read theories as in this article, but then that's what they are-theories. I wonder if we will ever be able to CONCLUSIVELY prove such theories. (other than using a time machine ;) )

    • Re:speculating (Score:5, Insightful)

      by splateagle ( 557203 ) on Friday December 06, 2002 @09:47AM (#4826137)
      "CONCLUSIVE" proof of anything is impossible. One day I expect we'll have gathered enough information to be able to settle comfortably on one martian theory over the others, but the whole point about science is that you don't get to *know* the answers, you just have to keep asking the questions.

      In that light this is an interesting article: personally I still think the atmospheric therories carry more wieght, but this is an interesting new way of asking the Mars question all the same.

      Real advances are often the product of what someone in an earlier post refered to as "National Enquirer Science", which might more neutrally be called "thinking outside the box"

      • Re:speculating (Score:3, Insightful)

        by freeweed ( 309734 )
        As Sagan so eloquently put it:

        "The fact that some geniuses were laughed at does not imply that all who are laughed ate are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown."

        Just because the odd breakthrough comes from some really bizarre sounding theory, doesn't negate the fact that most crackpots are just that - crackpots.
        • well said, although off the top of my head, I can't think of many breakthroughs which came from theories that *didn't* sound really bizarre at the time...

          incidentally your argument works equally well the other way up: just because most crackpots are crackpots, doesn't negate the fact that breakthroughs are often made with really bizarre sounding theories. ;)

  • I wonder, (Score:4, Interesting)

    by deathcloset ( 626704 ) on Friday December 06, 2002 @09:30AM (#4826064) Journal
    does rain precipitates differently in lower gravity? Certainly it would look a bit different hitting the ground, right? Maybe the Drops have to condensate bigger, so these giant raindrops come down at a half the speed of earths raindrops, like some boy-band video slow mo. Or maybe the raindrops are much smaller and it's a miniature version of earth rain. I wonder.

    • Re:I wonder, (Score:2, Informative)

      by October_30th ( 531777 )
      No.

      Gravity per se has nothing to do with precipitation. However, if it affects the small dust particles then it can also affect the precipitation.

      For instance on Earth the formation of water droplets would be practically impossible without small dust and ice particles in the atmosphere.

      • Now I'm not a physics/math type so I can't argue with you or really understand an explanation why but that doesn't make any sense. If gravity is the accelerating force then it should affect the speed of acceleration, though perhaps not the maximum velocity; that should be determined by the atmospheric pressure. Hence if it were to rain on mars today the drops would have a higher terminal V because the atmosphere is nearly nonexistent. Of course, there's not enough water in the atmosphere (if it still exists on mars at all) to have rain but you get what I'm saying.

        Could you post a simple explanation of how the size of raindrops is determined?

        • Sorry, my mistake. I read precipitation as precipitation formation.

          Sure the gravity affects the terminal velocity as well as does the density of the atmosphere.

          For a slow travelling particle, the terminal velocity is linearly proportional to the gravity and inversily proportional to a "friction" coefficient which, obviously, depends on the viscosity of the atmosphere. I do not know how exactly the viscosity/friction depends on the pressure (gas density) but I would expect the dependence to be rather weak (in a pressure range of 0 - 1 earth atm). Hence, the gravity would dominate the terminal velocity and, since the gravity on Mars is less than on Earth, the droplet terminal velocity would be less on Mars.

          All this is, however, complicated by the final size of the raindrop as both the friction and the gravity pull depend on it.

          The size of the raindrops is determined by the water vapor pressure inside the drop and outside it: How much energy would be gained/lost by creating a water surface and taking water molecules out through the surface, out of the droplet into the gas phase or vice versa. If you do the calculation, it turns out that under the ambient conditions in Earth's atmosphere, nucleation of pure water is highly unlikely. Evaporation of water molecules into the gas phase is energetically way too favourable in comparison with the forming of a water surface with surface tension. However, mix a nucleation center such as a dust particle, the coalescing of the molecules becomes much much easier.

    • Uhhh, Ive been studying things like this in Physics... based on my knowledge of air and gravity, I would say that rain would fall more slowly, and there would be less of it. With less gravity, rain falls at the speed it does becuase of air resistance. Im not sure how far it falls before the pull of the earth and friction of the air are at equilibrium, but im sure that happens relativly quickly. The air on a planet with a smaller amount of gravity would be thinner (less gravity to hold it down) and thus the rain would fall faster... but I dont think it would matter too much (if the atmosphere is thick enough to support cloud formation, it should be fairly thick near the surface of the planet). Oh yeah, and there would be less of it (rain) since the atmosphere would not be as thick, so there would be less cloud formation. Hope thats helpful =)

  • Atmosphere (Score:3, Insightful)

    by SmartGamer ( 631767 ) <sgamer@nOSPam.swbell.net> on Friday December 06, 2002 @09:45AM (#4826126) Homepage
    Mars has a denser atmosphere than Earth. While spaceborne objects would be a nice explanation for these formations- if a bit uncreative- it forgets the element of the atmosphere, which is the only reason Earth doesn't get pounded into rubble every meteor shower.

    Such objects tend to burn up in the atmosphere- and those which don't are rather uncommon, even geologically. What would be likely to make it through a thicker atmosphere?

    I think this is a long shot, personally. It's a possibility- but for it to be a real possibility, this would have had to somehow occur before Mars had its atmosphere. Which is not impossible- far from it- but not particularly consistent with the data.

    Admittedly, it's possible that the atmosphere was carried in a solid-frozen format on said bombardial objects, but that's even more of a stretch.

    • Re:Atmosphere (Score:1)

      by Anonymous Coward
      Mars has a much less dense atmosphere than Earth's.

      • I think we're confusing ourselves here. Carbon dioxide is heavier than our atmospheric gasses; however, Mars does have less of it. I think I'm wrong in my initial post, actually.

        My point still stands, however. While it would explain Mars having more impacts than Earth, it wouldn't explain that many.
        • While it would explain Mars having more impacts than Earth, it wouldn't explain that many.

          I'm not sure about that. Every time I play as Mars in SimEarth I always bombard the hell out of it immediately with at least 20 Ice Meteors to form an ocean.

          Who's to say that the universe doesn't play SimEarth the same way that I do?

    • Re:Atmosphere (Score:3, Informative)

      by entrager ( 567758 )
      Um... check your facts. The atmospheric pressure on Mars (a direct effect of the density of the atmosphere) is approximately 1/100th of the pressure on Earth. So actually, Earth has a FAR thicker atmosphere.
      • I'll defer to you. I find it more likely for you to be right. This is why I should not post to /. before I've had my morning caffiene.

        However, I still can't see as many objects as They seem to imply impacting with Mars. Space is not dense with objects, no matter what sci-fi movies may tell you.
        • Space isn't dense with big objects now, because most of them have settled into stable orbits (like the asteroids in the asteroid belt) or been sucked in by the gravity of much bigger objects -- i.e., the Sun and the planets. Earlier in our Solar System's history, it wasn't like that. For a looong time, all of the inner planets were getting the shit pounded out of them. The evidence for this is clear on Earth if you know where to look; it's more clear on planets like Mars and Mercury that don't have much in the way of weather to wear away the impact craters. Clearer still on the Moon, of course.
        • I couldn't agree more. However, note that Mars is close to the asteroid belt. In fact, theory suggests that the moons of Mars are asteroids that were captured when they got too close. I think that suggests that Mars is more likely to be hit than other terrestrial planets. As likely as this article suggests? I don't know.

    • Re:Atmosphere (Score:5, Informative)

      by Planetes ( 6649 ) on Friday December 06, 2002 @10:50AM (#4826484)
      "Mars has a denser atmosphere than Earth. While spaceborne objects would be a nice explanation for these formations- if a bit uncreative- it forgets the element of the atmosphere, which is the only reason Earth doesn't get pounded into rubble every meteor shower."

      Interesting. There's only one problem. You're incorrect. Mars' surface density is pretty close to the Earth's at 35000 meters. Roughly 0.015 kg/m3. Earth's at the surface (sea level) is approximately 1.2 kg/m3.

      The martian figure is from Nasa (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat. html)

      and the Earth figure is from any standard atmosphere chart available on the web. I don't have my texts with me so I just grabbed the one off USA Today's site. (http://www.usatoday.com/weather/wstdatmo.htm)

      Even if it were, Mars' atmosphere is much thinner and has a much lower pressure than Earth's. Meteors entering Mars' atmosphere stand a much better chance at reaching the surface than they would on Earth. Combined with the ambient atmospheric temperature of the planet's atmosphere, even the density wouldn't prevent this.

      The equation of state for an ideal gas shows this relationship. (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat. html)

      "Admittedly, it's possible that the atmosphere was carried in a solid-frozen format on said bombardial objects, but that's even more of a stretch."

      I have one word: "Comets" They are believed to be responsible for a large amount of the atmospheres of Venus, Earth, and Mars.

      Anyway, just my $.02.. :-)

      Daniel
      Aerospace Engineering major
      University of Central Florida - Orlando
      • Even if it were, Mars' atmosphere is much thinner and has a much lower pressure than Earth's. Meteors entering Mars' atmosphere stand a much better chance at reaching the surface than they would on Earth. Combined with the ambient atmospheric temperature of the planet's atmosphere, even the density wouldn't prevent this.


        True but, I claim, unimportant. Anything big enough to make a significant change to the Martian surface is big enough to get through the Earth's atmosphere and have interesting side effects when it lands here. A 10km body impacting the earth hardly notices the atmosphere.


        Paul

    • >While spaceborne objects would be a nice
      >explanation for these formations- if a bit
      >uncreative- it forgets the element of the
      >atmosphere, which is the only reason Earth
      >doesn't get pounded into rubble every meteor
      >shower.

      Eh? Did you read the article at all? We aren't talking about shooting stars here - we're talking about asteroids and comets that are miles across slamming into the planet. Objects that big wouldn't even notice the thin atmospheres of worlds like Mars and Earth. At the speeds they're traveling, they'd blow right through them in a couple of seconds and smash into the surface, releasing a tremendous amount of energy in the process and - if they're large enough - melting much of the subsurface permafrost on a world like Mars.

  • Your scientists are all wrong. (Score:3, Funny)

    by Lethyos ( 408045 ) on Friday December 06, 2002 @09:45AM (#4826128) Journal
    "Mars is essentially in the same orbit... Mars is somewhat the same distance from the Sun, which is very important. We have seen pictures where there are canals, we believe, and water. If there is water, that means there is oxygen. If oxygen, that means we can breathe"

    Spare me your "theories" of a harsh surface! If our democratically elected President believes we can breathe there, we can!
  • No.. Do not wish to flaimbait... But I feel so bogged down by some simple questions. We know very little about our nebor planet. How can we think we know perfectly about the galaxies, quasars, pulsars, neuteron stars, black holes and what not, millions of light years away?

    Sometimes I feel we know a lot.

    Juz sharing my thoughts guys..:-)

  • Misinterpreted article (Score:5, Informative)

    by Anonymous Coward on Friday December 06, 2002 @09:50AM (#4826156)
    This article is not quite clear in its interpretation of the research- the main source of the water would be ice on the planet, not on the meteorites.

    For a better article head to the bbc website http://news.bbc.co.uk/1/hi/sci/tech/2546923.stm

    The gist is that large impacts by asteroids or other bodies would heat water in subsurface ice, leading to massive flash flooding. They are speculating that very large impacts would have planet wide effects for short periods of time. This isn't that contrived, as there is evidence around small martian craters that suggest that ice has been melted leading to mud flows around the crater rim.

    However, this doesn't explain why the northern hemisphere of mars looks like a dessicated ocean floor, which suggests a relatively long period of warm conditions.
    • From the article:

      The impacts would have injected steam into the atmosphere, both melted from the surface and from the asteroids and meteors themselves.

      That is, they suggest the warm conditions you mention were created by steam and hot water. And the source of the water would not only be ice on the planet, but also from the meteors. The flooding and stormy rains that would follow would no doubt be able to shape the surface of the planet, creating all the valleys and such.
  • Okay, so the only currently relevant conclusion they are reaching is that life on Mars (if there is any) would have evolved to bloom and spread at massive speeds, like an even more extreme version of our desert plants. I can *kinda* see that since if there's usually no life in most places there's also no competition for anything that gets there. Given the Martian wind levels and a presumption of heavy rains then fast propagation is possible.
    Thass nice. So what?
    Well, it seems to me that if we begin to terraform Mars, or in fact, even build a base there that heats the surrounding area and spreads some moisture just by mistake, then we may get some sorta Martian kudzu [tbep.org] spreading everywhere. Sounds fine to me.
    Rustin

  • BBC version (Score:4, Informative)

    by jkcity ( 577735 ) on Friday December 06, 2002 @09:52AM (#4826167) Homepage
    BBC version [bbc.co.uk]

    a little nicer one the eyes in my opinion and has a picture too :).

  • Compelling (Score:1, Insightful)

    by Anonymous Coward
    I always thought that the vision of an erstwhile warm, hospitable Mars is based on little more than wishful thinking.

  • hell on earth too (Score:3, Interesting)

    by peter303 ( 12292 ) on Friday December 06, 2002 @11:07AM (#4826575)
    The first half billion years of earth were likely a molten meteorite hell too. Also most of the earths surface- the surfloors are recycled every 100-200 million years by plate tectonics, perhaps 20 times or so overall, wiping out much of the hellish scars.
  • For a hellish vision of Mars, look no further than Mission to Mars. I could not sleep for days after seeing that. I mean, come on, crying aliens!?!?
    • For a hellish vision of Mars, look no further than Mission to Mars. I could not sleep for days after seeing that.

      Which is ironic, considering Mission to Mars is widely regarded as a cure for insomnia.

  • ...this is just more of the Religion-loving-earth-is-only-place-with-life stories. Don't even TRY to tell me the entire planet was carved out with melting rocks. It was WATER people. Face it, the universe if full of life. Mars had & has water. Mars had & has life. When the first scoop of dirt comes back to Earth from mars in a decade or so, we'll see that life is EVERYWHERE.

    On a related story, the earth is NOT flat. Oh, and WE go around the SUN! Amazing, isn't it?

    • Re:Bullshit... (Score:3, Insightful)

      by Christianfreak ( 100697 )
      What? I don't believe the article has anything to do with religion. I find it truely sad that someone can't offer an opposing scientific theory because it doesn't meet with other people's preconceptions.

      Isn't that why the creationists are so annoying??? Because they can't make evolution fit with their preconceptions so its a lie?

      • I find it truely sad that someone can't offer an opposing scientific theory

        That opposing "theory" usually involves people who walk on water, a globe covered in water with one little boat floating around, etc.

        Most religious types don't like evolution because it forces them to realize that although there is a factual core to their religion, it is mostly stories. Stories. Back in the day, if you didn't understand something, it was attributed to God, demons, etc. Apart from the BSD devil, demons don't exist. Sickness is caused by GERMS, BACTERIA, etc. So don't bother with holly water, you need to visit your pharmacy.

        When I see people start comming up with so many reasons why water doesn't exist on mars, chances are it is because they don't want to find life on other planets. That fact alone would discredit most religions on this planet.

        Nothing wrong with religion. I was raised cathlic, and plan on a white church wedding (yum, honeymoon!). But to explain things, I turn to a page of science first, the bible dead last. And when I see scientists try to discredit water on mars, martian bacteria in rocks, etc, it is most of the time obvious that they are Sunday church goers to have to face their own fears that their religion is one big story, before they can let the science through.

  • It has been known for several years that there were catastrophic floods in Mars' past. Perhaps this is the explanation. Also, I believe I have seen studies that show that Mars could never have held a significant atmosphere because of its lack of a significant gravity field.
  • "25 huge asteroids or meteors, each about 60 to 150 miles in diameter"

    I cant believe this one. Especially if you look at our own impact craters. The Chixaclub crater in the Yucatan made rings 180 miles wide and the asteroid was estimated to be only 6 miles wide. Doesnt anyone think we'd notice the pothole left by a 150 mile wide asteroid? I would have to doubt there would be enough melt from teh asteroid or enough steam or water from the planet to wipe these out.

    Maybe if these guys are feeling really adventuresome they can read about the Sudbury impact (hit Canada 1.8 billion years too early) and the Vredefort impact in central Africa. These two left similar impact crater sizes and theyre still noticible 2 billion years after they hit. We found Chixaclub underneath all that marsh and muck and its 65 million years old (gets credited for dinosaur extinction).
    • Why do people who can't read keep getting modded as "insightful" here at /.?

      >Doesnt anyone think we'd notice the pothole
      >left by a 150 mile wide asteroid?

      Please READ the article:

      "Segura and colleagues used photographs of the Red Planet's surface and computer models to show that large asteroids or comets hit the planet 3.5 billion years ago."

      That's 3.5 *billion* years. Almost any impact crater from 3.5 billion years ago on the surface of the Earth would have long ago been eroded away, uplifted by faults into mountains, or subducted down into the mantle. In any case, they'd be difficult or impossible to identify now. Very little of the Earth's surface from 3.5 billion years ago remains intact. On Mars, it's a completely different story.

      There are a handful of large craters on Earth that are still identifiable after around 2 billion years, as this article [meteor.co.nz] makes clear. But the giants formed by large impactors from early in our solar system's history have long ago been erased (or at least thoroughly obscured) from the surface of this world.

      Our moon on the other hand has plenty of gigantic impact scars left over from before 3.5 billion years ago. For example, the gigantic Imbrium crater on the lunar surface is around 700 miles in diameter, and was formed about 3.85 billion years ago. There are several lunar craters in excess of 500 miles in diameter. Our moon is also home to the largest known impact crater in the solar system, the colossal 1,300 mile wide South Pole-Aitken Basin [nasa.gov].
      • The actual nasa article [nasa.gov] does say that there are photos of about 30 impacts that are older than 3.5 billion years, so I will give you that.

        She also does say that she is making the assumption that the craters and river valleys are the same age. I would like to know if any of those river valleys are interupted by crater impacts, showing that some of them are newer, leading to this idea that it has happened many times. I doubt some of these incredibly deep valleys could be carved with even a millenia of 6 foot annual rainfalls. The Grand Canyon is small compared to some on Mars and it has been forming with a rather steady flow (remember the used to erode much quicker, when it was prone to sudden burts of water) for for five or six million years, a geologically young feature.

        I still think Ms. Segura is missing some very important details when it comes to this theory.
        • That depends to some degree on the kind of rock that water was passing through. Was it hard, like basalt is here on earth, or was it softer stuff, perhaps some type of sedimentary deposit comprised of compacted regolith and permafrost?

          The Grand Canyon wasn't carved by the explosive melting of permafrost encased in a layer of regolith, either. With that much sediment in suspension, who knows how long it might take to carve deep features, even in relatively hard rock. Similar events could have been commonplace on the early Earth as well, but all trace of them would have been erased by geologic forces on this planet's active surface.

          You're also assuming the water carved all of the features we see today on Mars unaided. The problem with that assumption is that water would naturally flow through any existing cracks and low spots in the crust, ones that should have formed naturally as the planet cooled and its crust contracted.

          I'd say this theory is by far the best yet for explaining how the surface of Mars came to look the way it does today. I certainly find it more plausible than the assertion that Mars was once warm, wet and earthlike, sporting vast oceans. Perhaps that was the case *very* early in its history, but once the surface began to cool the tiny planet was far too small to hold an appreciable atmosphere at that distance from the sun, particularly given how dim the sun was over 3.5 billion years ago. Lighter greenhouse gasses like methane would have quickly escaped into space, while heavier ones like water vapor would have frozen out at the poles. Eventually, the surface of the planet became so cold even CO2 started to freeze, and at that point it was all over for Mars.

          Earth went through its own snowball phase at least once, perhaps several times during its evolution after its surface had finally cooled (a process that took far longer here than it did on tiny Mars, I might add). It apparently never became cold enough here for CO2 to freeze out of the atmosphere though, and Earth is massive enough to retain enough lighter greenhouse gasses (like methane) long enough for them to make a significant contribution toward warming the planet's surface. Eventually, that volcanic activity belched enough greenhouse gas into the atmosphere to free the oceans of their coat of ice. It didn't hurt that Earth was much closer to the sun than Mars either, or that by the time Earth was going through its big freeze, the sun was significantly brighter than it had been when Mars began to freeze over.

    • Vredefort is in South Africa, which is nowhere near central Africa.

      http://vredefortdome.co.za/ [vredefortdome.co.za]

  • the dead planet was occasionally bombarded by melting meteorites that carved out its distinctive craters and valleys

    Sounds like the condition of the streets where I live.

  • You know, this isn't anything close to the theories that have been tossed about in the past few decades concerning Mars.

    But you have to admit it's a well throught-out viewpoint, and contains no more hols than any of the other upproven Martian theories

    Point is people, we all need to take this in stride. Start favoring one theory with no rational evidence, and suddenly you become religion. I personally don't care, I'd rather hear what scientests have to say WHEN they land on Mars ( hopefully within my lifetime ). Until then, all we've got is pictures and a handful of samples.
  • That Mars sounds like a pretty interesting planet. Somebody should write some science fiction about it!

  • There is convincing evidence that Mars once had an ENTIRE OCEAN covering most of the northern part of the planet, early-on during the period of extensive meteor bombardment. This theory was further substantiated using a sensitive altimeter onboard the Mars Global Surveyor. Just take a look at this map: (It speaks for itself!)

    http://ltpwww.gsfc.nasa.gov/tharsis/shademap.html [nasa.gov] Pretty amazing, eh?

    I am aware that there is considerable debate on the matter, but I haven't seen convincing evidence that could explain the lack of cratering and extremely flat terrain of this northern region. Perhaps someone here who knows more about planetary science than I could provide possible explanations?

  • The true story. (Score:3, Funny)

    by rice_burners_suck ( 243660 ) on Saturday December 07, 2002 @12:43AM (#4830995)
    I refuse to believe this. Mars had an atmosphere and environment and ecosystem EXACTLY like the Earth, only much, much better. There were over a hundred trillion different species of animals and over nine hundred trillion different species of plants. The vegetation was lush and full everywhere except the oceans, which comprised twenty seven and a third percent of the planet's surface. Over a period of twelve thousand years, the people of Mars became incredibly intelligent and had built underground caverns of terrifying proportions in which they constructed enormous cities without damaging any of the plants above ground. All of their actions and technologies fit precisely within the balance of their planet's ecosystem such that no pollution or impurities took place. They began to explore other planets and had arrived at the farthest reaches of the universe. Then, a Martian child saw an interesting stamp on a little Martian girl's school desk and thought it looked cool, so he took it without telling anyone. The girl found this out and a fight broke out between her and the boy. As she could not prove who had done it, she became very angry and involved her parents. The boy's parents thus became involved in the argument and a family feud resulted. This escalated into a citywide riot, which resulted in a war between two neighboring cities, which had further involved their governing states. Within a matter of days after the stamp had been stolen, all of Mars was engulfed in a massive and horrendous world war which caused all the underground caverns to collapse onto the cities they contained, destroying them and the vegetation, and ending the fine balance in the ecosystem which made Mars such a nice place to live. The only remaining Martians alive were three astronauts on a Martian spaceship, a man and two women, who found themselves marooned on Earth when their spacecraft broke down while in orbit of the Earth's moon. They made an emergency landing, expecting that a rescue mission would be launched within a matter of days. That mission never took place. The astronauts thus reproduced into the human population as we know it today. That was approximately fourteen thousand years ago.
  • The heavy cratering on Mars (and elsewhere in our Solar System) and its change of Rotational Speed can be explained by the bombardment after planet Five went to pieces! Planet Five may, in fact, have been smaller in mass than Mars.

    -- Everyone knows that Death Stars were the biggest destroyers of planets, UNTIL the crew of the 'Dark Star' set off on their twenty-year mission of unstable planet destruction.------

    CORRECTED VERSION of MARS' HISTORY:

    Does anyone recall the fact that the mass of Phobos is TOO low for it to be a solid body?

    Now think, if Long, long ago in a galaxy far, far away the Empire built a THIRD Death-star but had to hide it because Luke and Hans kept blowing those things up .........
    then, when they thought it was safe to use it - no one remembered where they put it?!

    and of course, the skeleton crew manning it HAD to try out the BIG Weapon so they took a shot at the Fifth Planet - BAMM! Blown to asteroids, making the inhabitants of FOURTH Planet (where they had parked it in orbit ) extremely edgey!

    (They had to run around for a time avoiding a fantastic large-scale meteor bombardment which caused a great deal of damage!)

    "I hear a great tremour in the Force - as of a million voices crying out in fear and then, suddenly, nothing at all!"

    "You're imagining things Luke!"

    "Perhaps I am - it seems so far, far away - it would have to be in another galaxy infact."

    So, the inhabitants of the FOURTH Planet transmitted an ultimatum to the crew of the orbitting THIRD Death-star - that they would have to allow an inspection of ALL Weapons-of-mass-destruction .... in particular, a Planet-destroying Death Ray!

    "Or what?" asked the Death-star Crew.

    "Or we'll strike your space-station with our Barsoom V3 Super-gun!" they answered!

    So, what do YOU think happened millions of years ago?

    They had a VERY BIG gun battle between the Planet-destroying Death Ray and the Barsoom V3 Super-gun .........

    So what happened?

    Well, it was an atmosphere blown off that planet and big pieces blown out of the Death-star ......... everyone suffocated on that planet, and the skeleton crew manning the THIRD Death-star suffered terminal decompression!
    .

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