Writer makes a case that Large Space Habitats are easier to create than terraforming a planet (like Mars), and may be better to experiment with, before we try a whole planet.

So You Thought We Could Terraform Mars Quickly? Large Space Habitats Instead Open Solar System To Humans

SpaceX have a striking video showing Mars spinning faster and faster, transforming from the current red Mars to a planet with a small ocean and with the deserts tinged with green in seven revolutions. Of course that is poetic exaggeration - it wouldn't terraform in a week. So how long would it take?

 From article, (Perhaps terraforming is more like a grand goal for a mature civilization thousands of years old. But if so, there is much we can do as a young civilization, by way of building city domes, lava tube caves and free flying space settlements. We could settle the entire solar system right out to beyond Pluto with space settlements spinning for artificial gravity before the terraforming project has got off its starting blocks.

ith a small free space or lunar habitat of a few cubic kilometers, then we'd be bound to make many mistakes even with an experiment that small. But it is easily reversed (comparatively).

If there’s a build up of some problem gas, you can scrub the atmosphere. If there’s an infestation of some diseases, insects, or mold, say, you can treat it with chemicals or tackle it biologically and eliminate it. In the very worst case, if something comes up which you can’t fix - you can purge the atmosphere, sterilize it if necessary and start again, learning from your mistakes.

You can't sterilize a planet or purge its atmosphere and start again. Nor can you scrub it of problem gases or easily eliminate some problematical organism. Look at how hard it is for us to do anything about carbon dioxide amounting to an extra hundredth of a percent of the Earth's atmosphere, or to keep out invasive species from an island or continent, even for higher animals never mind microbes.

It might be a species introduced deliberately, because you think it will help with the terraforming, and then it causes problems you never expected. The European starling in the US, for instance, introduced by Shakespeare enthusiasts in the 1890s. That's not going to happen on Mars any time soon, as there won't be any birds in an atmosphere with little or no oxygen. But plants, yes, if they were successful. Kudzu might be a good analogy. US citizens were encouraged to plant it for erosion control, as a livestock feed and to make paper. Then it became a problem, smothering large areas, and it grows so quickly it is hard to keep it under check. Imagine a situation where some plant like that is out of control on Mars, what do you do?

Even feral camels are an issue in Australia. Deliberately introduced, but in such a vast continent, it's hard to get rid of them. Rabbits also, famously. Then moving in the other direction to the very small, diseases of microbes might also become a terraforming issue. For instance bacteriophages, viruses of bacteria, significantly reduce the amount of hydrogen sulfide produced by sulfur bacteria. This can be used as a biological control if the problem is too much H2S - but it may be a nuisance on Mars if your aim is to produce as much of the gas as possible to warm up the planet.


With a Stanford Torus or O'Neil habitat, or a lava tube cave or a city dome, none of these are an insoluble issue. You are not going to have a problem with feral camels, and rabbits also wouldn't be hard to deal with. With invasive plants like kudzu, at worst you have to sift the soil to remove the roots. Even sulfur bacteria, cyanobacteria, or microbes that could turn your water supply to cement - none of these are an insoluble issue. Even with bacteriophages, if you can't control them in any other way, just press the "reset button" of sterilizing the habitat, analyse what went wrong, and start again.

ettlements in space provide much more living area than planets can, for much less investment of effort and much less use of resources. As he says in that interview, our future, for most of humanity, is likely to lie in space habitats rather than on the surface of planets. From his interview in that video:

"I'm convinced that we will build space settlements in space, we will live inside small worlds, and we will eventually recognize that as the natural way to live. It is economical. You have just a relatively small amount of mass, and it is all used. In the case of the Earth, you've got an enormous mass, and almost all of it is not used. It's down deep where we can't get at it, and the only purpose is to supply enough mass to produce enough gravitational intensity to hold stuff onto the outside. And that's a waste! With the same mass you can build a trillion space stations carrying incredible numbers of people inside. And this is what we will eventually come to. I'm sure we will use the asteroid belt to build any number, thousands upon thousands, hundreds of thousands of space stations, which will eventually flee the solar system altogether."
Isaac Asimov

Anyway that's the idea. That planets are not where it is at for the future of space settlement. One calculation they did back then is that there are enough resources in the asteroid belt to build habitats for a thousand times the surface area of Mars (its surface area is also about the same as the land area of Earth).

For any here who are unfamiliar with it, the idea of mining the asteroid belt is to turn the materials there into habitats that spin to create artificial gravity. This is an idea developed by many engineers and scientists in the 1970s including O'Neil and some scientists at Stanford university who drew up detailed engineering plans for how to do it. This has been rather forgotten recently with all the fanfare about Mars.

It's not a case of living on Ceres. Nor is it a case of hollowing out an asteroid and spinning it and living inside it. It's a case of making a habitat out of asteroid materials and then spinning the habitat. And you can generate any level of gravity. Typically the design is to have a habitat under full Earth gravity because the designers assume that's best for human health. If a lower level of gravity is better they can just spin it more slowly. You could have a thousand times the land area of Mars as space habitats with Mars gravity if that was preferred. And you can have any level of sunlight you like and any length of day or night, using thin film mirrors to reflect the sunlight into the habitat, and then shades to simulate night and day.

I discuss it in my Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths

If you do it that way you end up with a thousand terraformed planets in terms of living area, for much less by way of megatechnology than would be needed to attempt to 'terraform' a single planet Mars. You can do it faster too, far faster, with the first habitats completed in decades.

And what's more, they can be customized to whatever gravity level you like. The atmosphere, temperature, ecology, all easily regulated and within your control.)

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