Naked Science Forum
Life Sciences => Cells, Microbes & Viruses => Topic started by: Paul Anderson on 24/01/2009 23:55:28
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Paul Anderson asked the Naked Scientists:
Hi Chris and team,
I see in my notebook I have jotted down, "Could micro-organisms be released on Mars in preparation for human occupation?". That seems a silly suggestion now, like releasing rabbits or possums in NZ. However, I suppose at the time I wrote that down, I was wondering about life starting on Earth, and whether we should encourage a similar evolution of life on Mars, or whichever planet might outlast Earth. If we just went straight ahead into planting trees in an attempt to speed up the process, I imagine the trees would not survive. Any comments?
Regards
Paul
NZ
What do you think?
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The problems I can see - apart from the risks of invasive species destroying anything that might be there or may have been there - are that it took millions to billions of years before the microbes were able to alter Earth - we're far too impatient to wait that long!
Chris
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Compared with Earth there is essentially no magnetosphere on Mars,
so Mars would lose oxygen generated by imported plants/microbes to space ...
Here on Earth we're protected from the solar wind by a global magnetic field (the same one that causes compass needles to point north). Our planet's magnetosphere, which extends far out into space, deflects solar wind ions before they penetrate to the atmosphere below.
Mars isn't so fortunate. Lacking a planet-wide magnetic field, most of the Red Planet is exposed to the full force of the incoming solar wind. "The Martian atmosphere extends hundreds of kilometers above the surface where it's ionized by solar ultraviolet radiation," says Dave Mitchell, a space scientist at the University of California at Berkeley. "The magnetized solar wind simply picks up these ions and sweeps them away."
"In 1989 the Soviet Phobos probe made direct measurements of the atmospheric erosion," he continued. When the spacecraft passed through the solar wind wake behind Mars, onboard instruments detected ions that had been stripped from Mars's atmosphere and were flowing downstream with the solar wind. "If we extrapolate those Phobos measurements 4 billion years backwards in time, solar wind erosion can account for most of the planet's lost atmosphere."
http://science.nasa.gov/headlines/y2001/ast31jan_1.htm
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Didn't Mars have some areas that are protected from the solar winds?
If such an area coincides with an area that has liquid water, it might be possible.
apart from the risks of invasive species destroying anything that might be there or may have been there
Wouldn't that be the point of terraforming? Changing the conditions to mimic those of earth?
Agreed, it's ethically debatable, but I don't think Mars is gonna talk back [;)].
Besides, terraforming would be completely in line with human behavior in the past and present.
it took millions to billions of years before the microbes were able to alter Earth
Maybe it took so long because of evolutionary trial and error. If we were able to engineer micro organisms with the exact purpose of altering Mars' atmospheric composition, it could take a lot less time, but still thousands of years ofcourse.
However, I would not get my hopes up Paul.
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The problem with Mars is, as RD has pointed out, that it has no magnetosphere. It's believed that Mars does have an iron core but it appears to have cooled and solidified, and it is this that has lead to Mars losing its magnetosphere, and as a consequence, its atmosphere.
No amount of surface terraforming or biological seeding is going to reheat and re-liquefy Mars's iron core to restore its magnetosphere, so any atmosphere generated by terraforming or biological seeding will be constantly lost to space.
It seems probable that Mars had a magnetosphere in the distant past, when its iron core was still molten, and so probably had a significant atmosphere and possibly standing water too, but even then its atmosphere would have been relatively rarefied because Mars has much less mass than the Earth and its gravitational field would not have held on to the atmosphere so well as on Earth. Its smaller iron core too, would have probably resulted in a weaker magnetosphere as well, so it wouldn't have offered as much protection from the solar wind as the Earth's does. Having said that though, Mars is quite a bit further from Sol so perhaps the wind wasn't as strong.
The problems don't just end with the issue of holding on to an atmosphere though. The lack of a magnetosphere also means that a lot of hard radiation from the Sun reaches the surface of Mars, so whatever manages to survive the rarefied atmosphere must also withstand high ionising radiation levels.
Mars is really quite an inhospitable place.