There are various schemes to provide Mars with a CO 2 atmosphere by causing the evaporation of the dry ice at the South Pole and in the regolith. Although no one knows how much is available from these sources, getting it to vaporize may not be too difficult and a reasonably thick atmosphere may be attainable in a hundred years or so. (1,2)

Other terraformers suggest the use of nanobots, tiny self reproducing robots that will rip the CO 2 apart physically. But nanotechnology is so far in the future that no one can really guess its capabilities or limitations. We do not need nanobots, only robots able to reproduce themselves. Presumably such machines will be roughly man-sized, not microscopic. Nor need they be able to reproduce every part of themselves, just the heavy parts. Light parts -- e.g. computer chips -- can easily be brought from earth. Even today a chip weighs half a gram, and two million of them weigh only a ton, so we can transport the brains for a robot army in a small space probe. Once there are many robots on Mars they can make solar panels or reflectors enough to cover the planet, and the power can be used to run cracking plants to split the CO 2

We can today build robots for mining and assembly, and will soon be able to make largely-self-replicating robots that can increase their numbers to any desired level at little cost to us. Cheap robot armies give us a powerful new tool for terraforming whose uses have barely been touched on here. Others should consider the possibilities that this idea opens up. For Mars we should have sufficient capabilities in fifty years, though it could be more or less. But surely we will have macrobots before nanobots, and whether it takes fifty years or a hundred and fifty we will have them, and be able to turn Mars' CO 2 to O 2 in a few decades. We should therefore abandon the idea that it will take a hundred millennia to terraform Mars, and turn our thoughts to a livable O 2 atmosphere in a century or less.

Terraforming