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#11
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Why we can't go to Mars (yet)
"R F L Henley" wrote in message .. .
unless and until we have robotically established conclusively that there is or is not life on Mars, we can't put humans on the planet because they will inevitably bio-contaminate it. Anyone agree? No. Mars has already been biocontaminated. I think the Russians didn't bother to decontaminate their 1971 lander and I don't think the Vikings were held to exacting standards of decontamination, either. Considering how inhospitable Mars is to terrestrial life, I say let the astronauts go. If the microbes on their suits and in any dumped turds and pee can prosper on Mars...go Earthlife! Mike Miller, Materials Engineer |
#12
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Why we can't go to Mars (yet)
No. But I suspect that the first men going to Mars might
well stay in orbit and direct rovers more quickly; with a time lag of seconds instead of many minutes, they can do a lot more. I think not, the current rovers will find their own path, mission controllers just tell the general directions. If i remember correctly, the Sojourner (or what was it) almost flipped over because the mission controllers wanted to manually control its moves and ended up rotating over huge (2x rover size) rock. After that they switched back to AI. I bet the Spirit could drive to distant rock with single command. |
#13
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Why we can't go to Mars (yet)
In article ,
Mike Miller wrote: No. Mars has already been biocontaminated. I think the Russians didn't bother to decontaminate their 1971 lander and I don't think the Vikings were held to exacting standards of decontamination, either. Sorry, wrong: the Viking landers were quite carefully sterilized, and if memory serves, the Russians made at least some attempt to sterilize their landers too. More recent landers, e.g. Mars Pathfinder, generally have *not* been sterilized, because it is now fairly certain that conditions on the Martian surface are so hostile that it's virtually impossible for Earth organisms to survive and spread. Attempts are still made to reduce the "biological load" carried, e.g. by careful cleaning, to minimize possible interference with future life-detection experiments. (And of course, any probe which carries life-detection experiments -- as Beagle 2 did -- must be sterilized to avoid false alarms.) -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
#14
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Why we can't go to Mars (yet)
"Steen Eiler Jørgensen" skrev i en meddelelse
. .. Should human activity on Mars bio-contaminate the surface, it should be no problem for a trained biologist to spot the difference between terrestrial microbes and organisms never encountered before. Not necessarily. If Terran microorganisms are introduced to Mars, and some of them survive and actually grow, they will be subject to an enormous selection pressure. A few decades might change them beyond easy recognition. Do microorganisms have enough junk DNA, which is not subject to selection pressure, to establish kinship? Also, there is the possibility that Earthlife has already been introduced to Mars, a very long time ago. Imagine a large meteorite strike on Earth; some of the ejecta somehow reaches Earth escape without being cooked, and Terran microorganisms survive in hibernation, well protected within the rock. Then this rock impacts Mars, in such a way that the central parts of the rock is not cooked. Discovering Mars-life with this particular kinship to Earthlife would be a considerable scientific find. Jon Lennart Beck. |
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Why we can't go to Mars (yet)
Raven wrote:
Not necessarily. If Terran microorganisms are introduced to Mars, and some of them survive and actually grow, they will be subject to an enormous selection pressure. A few decades might change them beyond easy recognition. "A few decades" - most certainly. I don't see it as a problem for the first handful of human missions. Besides, you wouldn't start looking for Martian life right below the habitation module. You'd probably go hundreds - perhaps thousands - of meters away from the base. Considering that the Martian surface is very hostile to organic life (oxidizing agents in soil, strong UV radiation), the probability for terrestrial germs to blow around in the wind AND for us to discover these germs is very small. Also, there is the possibility that Earthlife has already been introduced to Mars, a very long time ago. Imagine a large meteorite strike on Earth; some of the ejecta somehow reaches Earth escape without being cooked, and Terran microorganisms survive in hibernation, well protected within the rock. Then this rock impacts Mars, in such a way that the central parts of the rock is not cooked. Discovering Mars-life with this particular kinship to Earthlife would be a considerable scientific find. Absolutely. But I see it this way: If Mars is - or was ever - capable of sustaining life - and that's what we're trying to figure out - traces of this life should be present all over the planet. The idea of Mars as overall frigid and sterile, *apart* from unmistakeable signs, only found in e.g. the Hellas Basin, that Mars supported life long enough for it to develop, is - as I see it - extremely improbable. If life ever evolved on Mars, we should be able to find traces of it over most of the planet. Of course, if we find only small traces of what could appear to be terrestrial life brought to Mars billions of years ago, we'd probably find it only in specific locations. -- Steen Eiler Jørgensen "Time has resumed its shape. All is as it was before. Many such journeys are possible. Let me be your gateway." |
#16
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Why we can't go to Mars (yet)
"Raven" ro.com wrote in
message ... "Steen Eiler Jørgensen" skrev i en meddelelse . .. Should human activity on Mars bio-contaminate the surface, it should be no problem for a trained biologist to spot the difference between terrestrial microbes and organisms never encountered before. Not necessarily. If Terran microorganisms are introduced to Mars, and some of them survive and actually grow, they will be subject to an enormous selection pressure. A few decades might change them beyond easy recognition. Do microorganisms have enough junk DNA, I wish people would stop calling the "non protein coding" part of DNA for junk. See e.g. Scientific American, nov 2003 for the latest on this. which is not subject to selection pressure, to establish kinship? hmmm, again I think you are assuming junk here. As it is not (junk), it must be fair to argue that there is selection pressure on these parts as well. Also, there is the possibility that Earthlife has already been introduced to Mars, a very long time ago. And hopefully more to come! Ok, lets scan Mars for life, but surely it shouldn't hold back exploration of the planet. -Simon |
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Why we can't go to Mars (yet)
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#18
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Why we can't go to Mars (yet)
Mike Miller wrote: (Henry Spencer) wrote in message ... More recent landers, e.g. Mars Pathfinder, generally have *not* been sterilized, because it is now fairly certain that conditions on the Martian surface are so hostile that it's virtually impossible for Earth organisms to survive and spread. Well, you learn something every day. Old: clean. New: sloppy. Still, the end result is the same. Some terrestrial contamination has already made it to Mars. Terrestrial contamination occurred over billions of years through meteorite transfer Earth - Mars along the reverse process that brings Mars meteorites to Earth. Micro-organisms do survive the transfer. Dan |
#19
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Why we can't go to Mars (yet)
In article ,
Mike Miller wrote: More recent landers, e.g. Mars Pathfinder, generally have *not* been sterilized, because it is now fairly certain that conditions on the Martian surface are so hostile that it's virtually impossible for Earth organisms to survive and spread. Well, you learn something every day. Old: clean. New: sloppy. I should have added that there's a *reason* for this: sterilizing a spacecraft is difficult. It's hard to make chemical sterilization work well enough, and heat sterilization is terribly hard on electronics. (Sterilization-induced failures are thought to have been a contributing factor in the dismal early history of the Ranger program; the reforms that got Ranger out of its mess included discontinuing sterilization.) -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
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