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Possible Contamination, Bacteria hitched a ride to Mars
remcook
post Jul 17 2005, 10:57 AM
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http://www.timesonline.co.uk/article/0,,2089-1697332,00.html

QUOTE
FAR from discovering life on Mars, Nasa may have put it there. The American space agency believes the two rover spacecraft scuttling across the red planet are carrying bacteria from Earth, writes John Harlow.


Probably isn't the first time either. Can't believe old russian probes had any policy with that respect.
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Bill Harris
post Jul 17 2005, 11:41 AM
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Given that it is likely not possible to be sure that every spacecraft is 100.00000% microbe-free, it is possible that bugs have hitched a ride.

Of greater concern than the potential contamination with microbes would be the possible introduction of Terrestrial organics and DNA into the Martian environment. One way to find ancient Martian life would be to look for organic markers and DNA fragments; I'd guess that would be easier to find than a 3-billion year old fossil critter. For example, with the Rover's heatshield, we have introduced cork and the organic fillers used make the ablative coating. In 30. 50 or 100 years it would be a shame to not be able to determine if a DNA fragment is ours, or theirs.

--Bill


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tedstryk
post Jul 17 2005, 12:37 PM
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This tabloid article also says that the MER's key task is to detect life, something they are not even capable of unless bugs bunny comes out of his hole right in front of the camera or a camel walks by in a dust devil sequence. Note that the details of this are supposed to come out in a popular book. Seems to me the author is engaged in a bit of hype to promote his book.


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Phil Stooke
post Jul 17 2005, 01:44 PM
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"Can't believe old russian probes had any policy with that respect."

No, the Russians did sterilize their probes. But it's very true that it is "not possible to be sure that every spacecraft is 100.00000% microbe-free", and presumably we are getting better at that than before. I'm sure MER has way fewer microbe hitchhikers than Mars 3. I'm not sure if Mars Climate Orbiter was sterilized, but even if it was, it would not be to the same extent as a lander.

The guidelines don't call for zero microbes, but for only so many per square meter (I don't know the numbers). This isn't sloppiness, it simply is not possible to guarantee perfect sterility. But compared to you right after a shower, the MERs are sterile! (you dirty pig!) But if people ever go to Mars we can forget about sterilizing altogether. I don't mean we should stop taking precautions, but it will be close to futile. So we had better get some good work done with robots first.

Phil


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remcook
post Jul 17 2005, 04:01 PM
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exactly.
The chance of any Earth bacteria spreading widely across the globe is very very small IMO. Although they could be transported by wind, etc to almost anywhere I guess, I don't think they will screw up any possible detection of possible martian life (I assume they will be carefull if they find just one single piece of DNA and nothing else close by)
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djellison
post Jul 17 2005, 04:02 PM
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It's probably been done by nature already - ejecta from impacts on earth making it to Mars is not out of the question smile.gif

Doug
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Chmee
post Jul 17 2005, 05:23 PM
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QUOTE (djellison @ Jul 17 2005, 12:02 PM)
It's probably been done by nature already - ejecta from impacts on earth making it to Mars is not out of the question smile.gif

Doug
*


I would agree that if any contamination of Mars by Earth is at possible, it has already happened due to the exchange of ejecta from impacts. Its seems to me there is a sub-set of scientists who are zealots about microbe contamination and even call for no manned (and some call for no more un-manned) exploration of Mars until we can guarantee that no microbes are brought over.

Of course this is an impossibly high standard that would stop any future exploration of the planet. Mars is not a petri dish after all, but a dynamic planet
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DEChengst
post Jul 17 2005, 05:38 PM
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QUOTE (Phil Stooke @ Jul 17 2005, 03:44 PM)
The guidelines don't call for zero microbes, but for only so many per square meter (I don't know the numbers).  This isn't sloppiness, it simply is not possible to guarantee perfect sterility.
*


Sure you can. You'll just wreck the probe in the process tongue.gif


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tedstryk
post Jul 17 2005, 06:25 PM
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Those folks hold the guilt for the failure of the early Rangers. They demanded such stringent sterilization that their electronics were destroyed. These pseudoscientist planetary protection extremists ruined the missions (granted, I would not use such words to describe having concern about Mars - but for the moon, it was just plain stupid).


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ElkGroveDan
post Jul 17 2005, 08:41 PM
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QUOTE (remcook @ Jul 17 2005, 04:01 PM)
(I assume they will be carefull if they find just one single piece of DNA and nothing else close by)
*
As was the case with Oppy's Martian bunny.



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Bill Harris
post Jul 17 2005, 08:42 PM
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My comments were more philosophical than practical. This potential exists and we ought to be aware of it and put in the decision tree so that it can be considered and discarded. As noted, Earth and Mars have been have been lobbing rocks at each other for years. And since many organic molecules were likely present in the primordial accretion disk, as well as cometary material, there is a common organic dialect to begin with.

I have worked in the environmental field for the past 30 years, and as an _environmental_realist_, I know that past mistakes can be hard to undo.

Good discussion.

--Bill


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djellison
post Jul 17 2005, 09:10 PM
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QUOTE (ElkGroveDan @ Jul 17 2005, 08:41 PM)
As was the case with Oppy's Martian bunny.


*


The piece of airbag you mean smile.gif A Pancam spectra showed it to be the same as airbag material biggrin.gif

Doug
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Guest_BruceMoomaw_*
post Jul 17 2005, 09:14 PM
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Actually, I asked Jim Burke (the Ranger Block 2 project manager) about the sterilization issue years ago. He told me that the causes of the Ranger 4 and 5 failures are very well understood, and have nothing to do with sterilization -- but that the Ranger 3 computer failure which sabotaged their attempt to photograph the moon's farside during its distant flyby remains a puzzle and might have been sterilization-related.

In any case, the technology is much better understood now, as withness the lack of any sterilization failures on the Vikings (with the possible exception of the lander 1 seismometer failure, which also remains a puzzle). Back when the Block 2 Rangers were getting the treatment, some parts were actually warped out of shape by it and had to be retooled. Even then, I agreed with Arthur C. Clarke that on this issue it is MUCH better to be oversafe than over-careless.
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Marcel
post Jul 18 2005, 07:50 AM
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There's no reason to be concerned about contamination of Mars with "dead" DNA to my opinion. DNA without a supporting (alive) cell to expose it's properties is nothing more (or less) than organic matter. I believe that, in the martian environment, it will never be incorporated in some way that it could alter probable existing life there. Eventually the material (i.e. in the cork of the heatshield) will not be DNA anymore. Physical/chemical breakdown, wind action and solar radiation (especially UV) will take care of that by completely wiping out the delicate molecular structure.

I have the same feeling about bugs as well, though this could be more tricky. In the WEB of MER, the temperatures are balmy compared to Mars itself. But in there, they can't do much harm. In the end, they will not survive, simply because there's no energy source (FOOD) and/or water. Outside the rover, however, there could be a small chance that they meet the right circumstances (temp, nutrients, etc.) to flourish. But there's SMALL chance. Like Doug said: exchanging DNA (and maybe even bugs in hybernation) between Earth and Mars happened almost certain in history. As far as we can see now, it did not lead to life on Mars.......

Offcourse we need to take good care in sending up crafts as clean as possible. But by sending up things there, we KNOW we'll alter the planet in a physical, chemical and eventually maybe even biological way. It's a choice we made. Our urge to learn more about the planet is stronger than our concern to keep it clean and "original".
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dvandorn
post Jul 18 2005, 07:00 PM
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QUOTE (Marcel @ Jul 18 2005, 02:50 AM)
Offcourse we need to take good care in sending up crafts as clean as possible. But by sending up things there, we KNOW we'll alter the planet in a physical, chemical and eventually maybe even biological way. It's a choice we made. Our urge to learn more about the planet is stronger than our concern to keep it clean and "original".
*

The simple act of observing something changes it, to a greater or lesser degree. That's an immutable fact of the Universe (and is inherent in the very fabric of a quantum Universe).

You know what always tickled me? The fact that several of the Apollo missions included lunar atmosphere detectors in their ALSEP packages. And what did they find? They found that 99.9% of the Moon's atmosphere, at the time the detectors were active, was composed of the exhaust gasses from the most recently landed LM, the oxygen vented from the LM cabins prior to EVAs, and the water vapor and oxygen that escaped the PLSSes and suits. (A single J mission, if I recall correctly, was said to have trebled the *entire* atmospheric content of the whole Moon.)

In other words, the only really detectable atmosphere on the Moon was what we put there.

So, yes -- take reasonable precautions. But recognize where reasonability ends and zealousness begins.

-the other Doug


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