Originally Answered: What is the cheapest and fastest way to terraform Mars?
The Mars society have suggested it may be possible to terraform Mars as quickly as 1000 years with megatechnology - so that's what counts as a rapid terraformation. That is just as far as a CO2 atmosphere - okay for plants - but no birds or animals yet and humans would still need aqualung type oxygen breathers to survive. For full oxygen atmosphere they estimate it would be many more millennia. Chris McKay suggests 100,000 years.
Certainly the few generations ideas of the Mars Trilogy are currently way into the realms of science fiction.
Of course that could all change with nanotechnology and unlimited fusion power. But at present day, then 1000 years is the fastest suggestion I've seen.
In any case we have only just started our biological study of Mars. The surface is pretty much plain to view, so you can do at least some geology from orbit and assisted with ground truth.
But microbes on Mars would mostly be invisible from orbit - possibly some of the dark markings e.g. the dark dune spots could be partly due to microbial life also but we'd only know by studying them close up.
And we've only done a few measurements of Mars in search for life - mainly in the 1970s with limited results with equipment that we now know wasn't adequate for detecting life in the low concentrations on Mars and distinguishing it from the unusual chemical conditions we now know exist there, and also examined probably one of the least likely places to have life.
Also - Mars is very different from Earth. You can see that easily,
If you could magically transplant the Earth climate to Mars - then first the atmospheric pressure would drop to a third because of the low gravity - but also - it would quickly go into a snowball phase with all the oceans frozen over because Mars is so much further away.
It would slowly lose water vapour from dissociation in the upper atmosphere - and because there is no continental drift, then wouldn't return the CO2 to the atmosphere long term.
Before long it would end up just like present day Mars but with rather more ice on it. And then would gradually lose its atmosphere and then probably lose the ice gradually too long term.
So is easy to see, that if it is possible to terraform Mars, which nobody knows for sure then it will need a different solution from Earth with all the climate patterns and cycles of life designed afresh for Mars. - and no reason particularly to suppose that would happen automatically.
Indeed seed Mars with life, leave it to its own devices, and what you expect to get, eventually, is Mars just as it is right now :). Pretty much indistinguishable to the extent that it is quite possible that present day Mars did have life in the past, we wouldn't know.
It's similar to the snowball phases of Earth - when, for millions of years at a time - our planet would have seemed almost lifeless - covered with ice, no more life visible than there is on Mars. Mars is like that - except - without the ice because it lost most of its water.
Also, if left to its own devices, then after some attempt to terraform it, then it would probably unterraform again pretty much as fast as it terraformed, or maybe end up in some other end state maybe with thin but methane rich atmosphere poisonous to humans for instance.
I don't think it is necessarily impossible. But if some creatures in the future, possibly our descendants, do decide to terraform Mars, and do it successfully - they will surely know a huge amount more than we do currently about Earth and about exoplanets.
They will surely have much better climate models than ours, based on centuries rather than decades of data - or if they do manage it on decades of data - then perhaps as a result ofsome major leap forward in understanding - maybe based on study of exoplanets, and experience in closed system habitats in space, Stanford Toruses and O'Neil cylinders etc.
They won't be like us ,arguing endlessly about whether 0.01% of CO2 really has caused global warming and deciding what to do about it if anything. If we are that uncertain about our own climate - we are of course a long long way away from knowing how to terraform a planet!
And - it's not a good idea to experiment with a planet. In any case what kind of an experiment is it, with no controls, and no way to undo and redo the test? If we want to experiment, use the more controlled conditions of a Stanford Torus. Which would also cost far far less to construct and be completed within decades instead of getting our first results centuries or millennia into the future.
For more about this see my other answer for a very similar question here:
Robert Walker's answer to How long would it take to terraform Mars?
and my article Trouble With Terraforming Mars
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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