Planet colonising on the cheap...

I gather that the Mars Rover project is looking for signs of liquid water, methane and perhaps other indicators of the existence of life, or at least a former decent habitat, on Mars.

If they don’t find any sign of life after a thorough search, are there any bacteria we could shoot up there in a space-pod to start from scratch? Something anaerobic with an appetite for red dust? If not, perhaps we could genetically adapt some to survive?

If we did this to a few planets, at least we could prolong life in the universe past the point where we turn Earth sterile…

Terraforming is the name given to adapting extraterrestial planets to become more environmentally earth-like. Here is a paper telling you how to accomplish it with mars. Warning: lots of equations and graphs and stuff.

I’m not sure what other planets you had in mind; in our solar system, Mars seems about the least hostile by quite a margin, but there are still some really big problems to be faced with the idea of terraforming it; chiefly that it’s too tiddly to permanently hold a normal, breathable atmosphere. Venus would be more useful, if it wasn’t for the abundant boiling hot acids.

Planets outside our solar system are quite likely to remain unreachable for the human species.

Well, other than the Earth, of course.

And there’s no way that this would be a plan to continue life after we sterilized the Earth. There’s no conceivable way that we could render Earth anywhere near as sterile as Mars is currently. We might be able to kill off ourselves, and perhaps take a few other species with us, but the bacteria will survive at least until the Sun goes red giant and swallows the planet.

Now, then, your best bet for a terraforming organism would be some form of lichen. There are lichens on the Earth which would be able to survive both the temperature extremes and the lack of oxygen or other gasses in the atmosphere. The lack of overall pressure might conceivably be a problem, but I’ve never found any information on that. As an added bonus, some lichens secrete acids which would release CO[sub]2[/sub] from the rocks, and if they’re dark in color, they’ll increase solar heating of the surface, both of which would help to make the planet more hospitable for other organisms to follow.

Well, you say that, but how comfortable are you, really?

According to the Wikipedia (http://en.wikipedia.org/wiki/Mars_(planet)), the mean surface temperature of Mars is 210 degrees Kelvin (-81.7 Farenheit). Even if we could get it to hold an atmosphere, it would still be awfully cold, even by the standards of penguins and polar bears.

Surely a significant part of the reason for the cold surface temperature is the comparative lack of atmosphere, isn’t it?

Mangetout is correct – the results of causing Mars to have a substantial atmosphere would produce a climate cold by Earth-temperate standards but liveable – think Edmonton, Fairbanks AK or Siberian cities as comparisons. (Of course, “causing Mars to have a substantial atmosphere” is not a trivial problem – “First, catch the rabbit.”)

The Hellas basin in the South Temperate Zone presently has (barely) enough atmospheric pressure to permit liquid water – though 95%+ of the time it is too cold to do so. It’s the only spot in the Solar System besides Earth where liquid water exposed to the atmosphere can exist, AFAIK (the “exposed” phrase is to cover situations like Europa where liquid water may be protected by a thick layer of ice).

There are speculations, whether borne out by lander tests or not I don’t know, that some Martian rocks may have a great deal of bound oxygen and/or water, which could do a lot towards Terraforming the planet.