Methane-Eating Bacteria May Presage ET Life 91
asukasoryu sends along an intriguing piece in light of our recent discussion of possible signs of life on Saturn's moon Titan. "Researchers have discovered that methane-eating bacteria survive in a unique spring located on Axel Heiberg Island in Canada's extreme north. The subzero water is so salty that it doesn't freeze despite the cold, and it has no consumable oxygen in it. There are, however, big bubbles of methane that come to the surface. Lyle Whyte, McGill University microbiologist, explains that the so-called Lost Hammer spring supports microbial life, that the spring is similar to possible past or present springs on Mars, and that therefore they too could support life."
The problem with using extremophiles as models (Score:5, Insightful)
Organisms on Earth which live in extreme environments probably evolved from related species which live in less extreme environments. I have no doubt that there are Terrestrial organisms which could survive in certain environments on Mars, but if they have counterparts on Mars, where did they come from? If they evolved on Mars, there has to have been an environment in which such evolution could have taken place over some kind of condition gradient, from less hostile to more hostile. If they came from Earth, you need a hell of a story about how they got there -- not only are meteor strike ejecta a lot less likely to make it from Earth to Mars than the reverse, you have to envision one piece of rock that just happened to be carrying a viable population of (already rare, even here on Earth) extremophiles that were suited for certain (also very rare) Martian conditions, and landed in just the right place.
If we can ever confirm that Mars had a more life-friendly environment for a significant portion of its history, of course, then these objections can be disregarded. But until we have much more evidence of that than we currently do, I'd be very surprised to find native life on Mars. It's much more likely that if anything is living there, it was carried there by probes from Earth -- and even that seems like a one in a million shot.
Re:As a wise fictional character said... (Score:5, Insightful)
Life finds a way, ladies and gents.
We don't know that. We know that once life gets going it seems to be very resilient and manages to find a lot of different environments to colonize. But we don't know how easy it is for life to start. If life starting is really difficult, then it may be that Titan and Mars are completely barren. What this sort of thing does mean is that if there ever was life on Mars, there's a decent chance that there's still some.
Re:The problem with using extremophiles as models (Score:5, Insightful)
About 300kg of rocks make their way from Earth to Mars every year. The reverse is more, about 500kg. The total of "hospitable" rocks that might harbor stowaway life for an Earth to Mars transit is about 150kg/year [tpg.com.au]. So, you see, we're constantly seeding life on Mars.
Re:As a wise fictional character said... (Score:5, Insightful)
Please mod into oblivion, or re-reply yourselves and be damned with the consequences
Re:As a wise fictional character said... (Score:2, Insightful)
it strikes me that far from being the sterile lifeless environments that other non-earth planets are assumed to be, that in fact every planet is likely riddled with life in some form, at a microscopic level at the very least. To assume otherwise is perhaps simply subscribing to that eternal 'truth' that humans believe that they are somehow special in the universe. The ancient greeks, as wise as they were, once believed the earth to be at the very centre of things.
One human may be special to another, but in an almost infinite universe our status of being special looks shaky. Likely 'fairly common' is the best we could ever hope for on a universal scale.
It seems absurd to me the idea that life can only exist in some arbitrary narrow range of conditions? I think we may underestimate that which is life.
Re:No viable Mars-Earth rock exchange happening no (Score:3, Insightful)
There's been an incredible number of papers on the subject, and the overall conclusion is that lithoautotrophic extremophiles most likely do survive the trip. Your objection to the timescales involved is anthropomorphic thinking. On geological timescales the exchange of meteorites between Earth and Mars is constant, and so yes, we are constantly seeding life to Mars.
Re:As a wise fictional character said... (Score:3, Insightful)
Re:As a wise fictional character said... (Score:3, Insightful)
but until we find life that's without a doubt non-terrestrial
It might be difficult to prove that any organisms found elsewhere in the solar system aren't at least distantly related to those on Earth. The solar system being as old as it is, it's entirely possible that over the last three and half billion years or so micro-organisms have traveled between the planets. Deep analysis of their DNA won't necessarily be conclusive, if the organisms were transported between the planetary bodies say three billion years ago it's likely they've evolved and changed significantly since then to fit their environments.
It's also possible that life here on Earth had more than one start - there has been some fascinating research on that subject lately and it's a good point to ponder, our earliest apparent evidence of life here on Earth was back when the planet was still subjected to potential bombardment by very large asteroids, and geological upheavals that could have terminated many early starts. For that matter it's possible that life started elsewhere in the solar system and only gained a foothold here on Earth because the environmental conditions were more suited.
We may never know for certain, unless someone invents a time machine and spends a few thousand years taking samples over large timescales...
SB
Re:Methane eating bacteria? (Score:3, Insightful)
Re:As a wise fictional character said... (Score:3, Insightful)
Since at the moment our supplies of food are depleted and the women in the cave are complaining about the children crying all the time because they're hungry, it might not be a bad idea for the cavemen to invest their time hunting for food and postpone the building of the next raft till after the next migration season, when the cave is full of food again.
If you wait until you have no problems before you start investing in the future, you'll never invest, because there will always be problems.