Earth microbes may contaminate the search for life on Mars


Bacteria common to spacecraft may be able to survive the harsh environs of Mars long enough to inadvertently contaminate Mars with terrestrial life according to research published in the April 2010 issue of the journal Applied and Environmental Microbiology.

The search for life on Mars remains a stated goal of NASA's Mars Exploration Program and Astrobiology Institutes. To preserve the pristine environments, the bioloads on spacecraft headed to Mars are subject to sterilization designed to prevent the contamination of the Martian surface.

Despite efforts made to reduce the bioload on spacecraft, recent studies have shown that diverse remain at the time of launch. The sterile nature of spacecraft assembly facilities ensures that only the most resilient species survive, including acinetobacter, bacillus, escherichia, staphylococcus and .

Researchers from the University of Central Florida replicated Mars-like conditions by inducing desiccation, hypobaria, low temperatures, and UV irradiation. During the week-long study they found that , a potential spacecraft contaminant, may likely survive but not grow on the surface of Mars if it were shielded from UV irradiation by thin layers of dust or UV-protected niches in spacecraft.

"If long-term microbial survival is possible on Mars, then past and future explorations of Mars may provide the microbial inoculum for seeding Mars with terrestrial life," say the researchers. "Thus, a diversity of microbial species should be studied to characterize their potential for long term survival on Mars."

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Apr 27, 2010
It will almost undoubtedly be DNA based regardless, so it may be hard to tell if it's indigenous.

Why do you say that? DNA is only one of 4 theorized methods of genetic information storage. That's jsut what we can imagine, and as we know, human imagination is greatly limited by experience.

Apr 27, 2010
Is this the reason NASA has forgotten to include any life detecting equipment on Mars surface missions for ca. 35 yrs since the successful Viking missions?
Did Viking detect contamination from Earth or life from Mars?

Apr 27, 2010
Is this the reason NASA has forgotten to include any life detecting equipment on Mars surface missions for ca. 35 yrs since the successful Viking missions?

Did you miss the Mars rover missions? You missed out.

Apr 27, 2010
When and if we find life on Mars you can be sure the skeptics will say it's from earth. It will almost undoubtedly be DNA based regardless, so it may be hard to tell if it's indigenous.

Unless this Mars lifeform starts shooting at us.

Apr 27, 2010
Skeptic's right -- the mars lander missions had a small suite of instruments to test for water and microbial life... where you been

Apr 27, 2010
Professor Chang, a reputed genetic researcher at the Human Genome Project, has this to say about our origins:

Perhaps if this really is the case, then all this 'contamination' is utterly irrelevant, as life has been cultivated in accordance with biological necessity. It doesn't therefore matter where life is 'found', but rather that it happens to exist at all.

Apr 27, 2010
That's probably how we got here. Some alien didn't wash their hands when they packed up their Earth probe and voila!

Apr 27, 2010
DNA is complex. Nature doesn't usually do unecessary complexity. If complex life didn't need such a complex chemical to exist and evolve it would have found a simpler way to do it. If life is found elsewhere it will be carbon based because only carbon molecules can create the complexity required for life, there are estimated to be around 2 million different proteins in the human body. No other element can do that. If it is alive it will be carbon based and the smart money will be on DNA, especially if it's found in this solar system.

I'm not poking holes in what you're saying, I just think you're limiting the possibilities. Ammonia based life (which is a potential on Mars, and some of Jupiter's moons) most likely wouldn't be based on carbon centric DNA strands. It would most likely engaged in Nitrogen bonding.

Plus think of the differences with Silicon based life. You can effectively sub in Silicon in place of Carbon on most of those molecules.

Apr 27, 2010
@fourthrocker: please define "life" and explain why DNA is required. You actually seem to be way out of your element on this.

Apr 27, 2010
To anyone who doesn't know:

The Viking missions had several instruments designed to detect life. While some of the instruments confirmed the presence of life, others did not. Regardless, the most interesting part is the same instruments were tested on Earth with soil samples known to contain life and produced the exact same results.

Apr 27, 2010
Yes but from what I understand the tests that did detect life were not an indicitive test and the ones that failed were environmentally biased producing negative results in all cases.

Apr 27, 2010
Not only that, look at RNA, and the theorized RNA world.
And i'm pretty sure there has been a lot of chemicals found, including their opposite handedness, that aren't really used in life but can be.
There was even that team who managed to replace the DNA backbone with a metal.
As Skeptic said, silicon can take the role of carbon in a number of molecules.

There could well be other methods that exist too, and it was just RNA and DNA that won over.
Some of those other methods might not even be possible in our atmosphere now.

Titan could well be filled with life, admittedly simple, but still life.
It is an incredibly active planet, filled with radiation that could result in some interesting forms of life evolving to take advantage of that.
Going by the crazy things we have been finding on here in the past couple decades, especially all these extremophiles (especially that one that doesn't depend on oxygen), i think i can say with all probability that their is life on Titan.

Apr 28, 2010
The Viking experiment that detected "something" on Mars produced CO2 that rose and fell with the time of day and continued for ca. 45 days. NASA says that it was caused by an unknown, mysterious, inorganic chemical reaction. The designer of the experiment says that it was clearly an indication of life. Who is correct?

Since Viking NASA has not sent any instruments to specifically detect life processes or by-products of life such as optically pure aminoacids, though those instruments would be much smaller, sensitive, and specific than what was sent on Viking and on that obfuscation mission Phoenix. That mission, sent to the polar region where any life would have been frozen and decomposed millions of yrs ago from radiation, should have been sent to wet areas (seen in photographs) at lower latitudes so it's primitive mini-muffle furnace could decompose any organic compounds to inorganic carbon, nitrogen, water, etc. Why? Only NASA knows.

Apr 28, 2010
does it really matter if any detected life did originate from earth.

Yes, the religious and ethical implications are enormous. They are on opposite sides of the spectrum, but they exist.

Apr 28, 2010
does it really matter if any detected life did originate from earth. The fact a microbe of any type could survive on the red planet makes it abundantly clear (at least to me) that there should be other life out there, and that our little blue planet is NOT the end all, be all, for life to exist.

Well the problem is it obscures whether life on Earth came from Mars if we contaminate the planet with non-native life before we can perform the research.

May 01, 2010
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May 01, 2010
Sounds like a late and microscopic instance of panspermia that is a well accepted theory of the origin of life here on Earth. It may be our ethical duty to (re)introduce life to Mars, perhaps correcting for its untimely failure there. Indeed, like many organisms, once Gaia has reproduced she may wither and die, accomplished.

Our DNA insists that we seed the Universe with the pathogen that is Man. Of course we will take our critters along as well.

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