Many people have written much on the topic of terraforming (changing a world to be more suitable for human life, more like Terra.) While early discussions focused on Venus or Mars, planets around other suns have been considered, as well as the large moons of Jupiter and Saturn.
Terraforming a planet is likely to require centuries or millennia at best, making it an unlikely venture. But in principle, the cost might be low (largely seeding with a mix of bacteria, algae, and eventually the rest of a viable ecosystem). It might happen, at least if the ethics of modifying another place to our liking is ignored.
What do you get if you successfully terraform a planet? You get a whole new world to explore and exploit, a new home for millions or billions of people. The downside is that it's at the bottom of a gravity well, which presently is a very expensive place to go to. Or rather, to get back from. It's easy to go to the bottom of a gravity well, of course.
Personally, I think it is easier, cheaper, and ultimately much more profitable to "terraform" asteroids and comets by hollowing them out and spinning them for gravity. You end up with much more room for people, plus a lot more resources for development. And these worlds are easy to visit.
Note that we are already busily terraforming our own planet Earth, or un-terraforming it, depending upon who you listen to.
Most would agree that we are in the middle of a process that can potentially change the surface and ecology of the entire planet. It is an experiment, and not a scientifically sound one (there is no control). It is driven by short term economics (of which population growth is an aspect), and fueled by the massive burning of coal, oil, natural gas, and (even more unfortunately) forests. Additional questionable experiments include the destruction of fisheries (and the unintentional but ongoing and significant evolution of fish stocks to make themselves less desirable to humans as a way to survive).
I will argue that this terraforming practice, while in most ways unfortunate and misguided, is still a valuable learning experience. Because someday, we will need to terraform our home planet in earnest. A new ice age is nothing to laugh about, it is serious business. Some day, we will have to warm up the planet to survive.
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2 comments:
Hello Stephen,
I stumbled in your blog and just started reading it.
About "Terraforming" which is indeed a fascinating topic, I am a bit pessimistic about the "biological" part.
Few years ago I was in New Zealand for vacation and I learnt there what a disaster on the local ecosystem was done by the europeans simply by bringing there cats, rabbits, dogs and pigs.
Well, spreading bacteria and other living creatures on a planet where no living creatures are there at least is not going to destroy anything, but I feel that chances for success are still pretty low.
Eco-systems are quite a complex thing. I don't think it takes a god to build them, but still I think that our knowledge is pretty far from being able to produce something predictable from scratch on a planetary basis.
Maybe in some small "domes"...
Also small asteroids would not provide radiation filtering we usually get from the atmosphere, which would prove unsuitable for most of the life-forms we know.
Besides that spinning them so that the time distance between day and night would be like 15 minutes may give me some sleeping problems :)
I keep on reading...
francesco, my primary point on terraforming is that, while possible, why bother? You end up with a potentially livable environment stuck at the bottom of a gravity well. And you'll have to wait a few centuries for even that.
I think we should hollow out asteroids and comets (or use their raw materials to build habitats), spin them for gravity, use a huge amount of rock/slag/ice as radiation and meteor shielding, and live inside.
The "terraforming asteroids" quote in my post wasn't meant to be literal. We'll just build homes, and use technology (including greenhouses or the equivalent) to provide air, food, and water.
All that exterior mass provides more than enough radiation shielding. A ten meter thick layer of ice provides as much protection as Earth's atmosphere; you'd want more rock than that because hydrogen is better at stopping certain types of radiation. And why skimp when you have megatons of mass to work with.
You are absolutely right; ecosystems are quite a complex thing. It will be difficult enough simply to maintain (for an indefinate period) the farm, or greenhouse, or algae and fish tanks that are needed to recycle CO2 and waste products into food, oxygen, and potable water.
Indeed, that likely the biggest challenge in creating an asteroid or comet based civilization. We have much learning to do.
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