This is topic Martian Contamination in forum Books, Films, Food and Culture at Hatrack River Forum.

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Posted by Szymon (Member # 7103) on :
I just read a really convincing thesis on possible contamination of Mars by all kinds of human made probes, rovers and stuff. Apparently those microorganisms are very livable. They can easily survive in martian climate and even procreate. Moreover, it's been confirmed that there is some water there.


experience with missile impact indicates that even at impact velocities of 0. 6 km/set or less, a significant fraction of the missile's mass is not in the impact crater and is unrecoverable. The shells and grenades used in bacteriological warfare indicate that contained microorganisms will survive such impacts

In a period of minutes - less than the time for many unshielded terrestrial organisms to accumulate an ultraviolet mean lethal dose on Mars - fragments travelling in parabolic trajectories at 6 km/se will cover a lateral distance N 1000 km. A typical microbial load of a surface-sterilized spacecraft assembled under clean room procedures is 107, distributed uniformly over the Martian surface, it results in a loading density of one microorganism every 10 km2 on Mars.

Do you have any information on whether all those probes are/were sterilized any better? Is it even possible? Because I sincerely doubt it. Let's assume that the first human-made artifact to reach Mars' surface was Mars 2, made in USSR. They probably had much more things to think about than possible contamination. And it was USSR. In 1970's.

So after 40 years we probably have couple of hundred thriving bacteria colonies. Even if there was any life there before Mars 2 - will we never know?

(for source just a sentence from quotes)
Posted by Lyrhawn (Member # 7039) on :
1. Wouldn't DNA be able to differentiate?

2. Isn't the fact that Mars could sustain life good enough?
Posted by Szymon (Member # 7103) on :
1. You mean that the New Martian Bacteria would change due course? Or that we would be able to differentiate ET life from the one we know? Cause we wouldn't.

2. Yeah, well, such small creatures can live almost anywhere. Bacteria on Apollos went all the way up, all the way down, and still lived. And in the middle of a volcano. It changes nothing for us. If we find a life form or life remains, we won't be sure if it isn't ours.
Posted by ak (Member # 90) on :
I think it will be fairly easy to tell earth bacteria from martian. Everything alive on earth is descended from an organism called blue-green algae, but is actually best described as photosynthetic bacteria. Yet the prokaryotes and eukaryotes who later descended from them have different but related genetic codes. If bacteria found on Mars has the identical genetic code to those on earth, it's very probable they originated on earth. However, if it's different, but related, but more distantly related than the genetic code used by other organisms on earth, then that would certainly be a fingerprint of life from another planet. I'm not an expert, but from what I know, it should be fairly obvious.

Here's another thought. Meteorites have fallen to earth that originated on Mars, in impact events. Presumably the opposite is also true, that meteorites originally from Earth have fallen onto the surface of Mars. If conditions on Mars are suitable for growth of earth microbes, wouldn't it have been contaminated long ago from those meteorites, with no need to wait for human-made probes?
Posted by Lyrhawn (Member # 7039) on :
Or for that matter, innerstellar meteorites that came from a third party that landed on both.
Posted by Szymon (Member # 7103) on :
Even so, any findings of life probably won't be as spectacular as we would want them to be...
Posted by Lyrhawn (Member # 7039) on :
I think LIFE ON MARS will still be a pretty spectacular headline when and if it's discovered in the near future.

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