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Biological debris on Mars
If at some future time evidence of biological presence on Mars is ever
discovered (e.g. bacteria), how will scientists be sure it's not just contamination from previous Earthcraft that landed there? Surely NASA doesn't claim that it's probes etc are guaranteed sterile when they land... or do they? Orilly (Named after the time I get up) |
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Orilly wrote: If at some future time evidence of biological presence on Mars is ever discovered (e.g. bacteria), how will scientists be sure it's not just contamination from previous Earthcraft that landed there? DNA testing. Earth bacteria aren't likely to be mistaken for martian bacteria. Surely NASA doesn't claim that it's probes etc are guaranteed sterile when they land... or do they? No guarantees are made, but NASA has been trying. Mike Miller |
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Actually, NASA tried with Viking landers and there was an attempt by
treaty at a no-contact with Mars for 50 years (expires in 2019), meaning that even unsterilized orbiters had to be in orbits that will not impact the planet for that long. (The reasoning at the time apparently was that by then, manned landings would have determined the question.) It's not NASA that you should worry about having contaminated Mars; the Soviets were a lot more lax in sterilization than they probably should have been. Their technique for navigation was basically put the probe on an impact trajectory, then move to flyby or orbit in the last several days before encounter. At least one unsterilized probe meant for a flyby failed while still on the impact trajectory (Zond 2), and is thought by some to have crashed on the planet in 1965. And of course there were Mars Observer (1992) and Climate Observer (1999), both of which were unsterilized orbiters which may have hit the planet. |
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In article ws.net,
Orilly wrote: If at some future time evidence of biological presence on Mars is ever discovered (e.g. bacteria), how will scientists be sure it's not just contamination from previous Earthcraft that landed there? Given the harshness of the Martian surface environment, it's grossly unlikely that any bacterial hitchhikers on past spacecraft have grown and spread. Any contamination will almost certainly be in the immediate vicinity of recognizable debris. Martian life, if there is any, is far more likely to be found underground, in places like hydrothermal vents. No spacecraft have been there. Surely NASA doesn't claim that it's probes etc are guaranteed sterile when they land... or do they? The Viking landers were indeed sterilized -- necessarily, since they were carrying life-detection instruments. More recent landers are not, but efforts are made to reduce the level of bacterial contamination, precisely to minimize the chances of confusing later life-detection efforts. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
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"Orilly" wrote in message eenews.net... If at some future time evidence of biological presence on Mars is ever discovered (e.g. bacteria), how will scientists be sure it's not just contamination from previous Earthcraft that landed there? DNA testing would be a good place to start. |
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Paul F. Dietz wrote: Why do you say that? Because, despite any similar origins, there's probably going to be some obvious genetic differences. Those bacteria in terrestrial soil do not have genes so strikingly different from identified terrestrial bacteria that scientists might suspect they're alien, like some do with the odd Archae microbes. Mike Miller |
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