Friday night I watched The Biggest Little Farm. It really was a wonderful film, filled with tender little scenes and a powerful vision of ways to build a more resilient agricultural base for our country and the world. It's not a spoiler to say that film is about a couple who set about to create a sustainable farm by building up a vibrant ecosystem on a failed 200-acre farm in the California hills north of LA. The place starts out as a dust bowl. Essentially, they are terraforming the earth.
Well, that phrase "terraforming the earth" came to me later. It struck me as interesting and stayed with me. At the same time that we have used energy from fossil fuels and synthetic fertilizers to feed billions, we have also created deserts and fantastically fragile monocultures. The fact is that, as a species, we're pretty horrible at terraforming earth and the idea we could terraform another planet like mars seems, well, just far-fetched.
So let's think about it! It'll be fun!
At this point, it seems to be true that mars once had an atmosphere and oceans. When the martian geodynamo weakened, its magnetic field collapsed and the air and water were essentially stripped away by the solar wind. (e.g., It's Official: NASA Announces Mars' Atmosphere Was Stripped Away by Solar Winds). So I'm thinking small-scale greenhouses are a really sketchy premise for an effort to colonize another planet. To settle mars, we'd have to re-establish that planetary magnetic field. Of course, there are a few obvious ways to do that.
- We could somehow inject more iron and radionuclides into the core of the planet to heat it up. Seems hard.
- We could gradually haul asteroids to the planet until it's mass increased enough to undergo something like earth's iron catastrophe. Might take millions of years and and we would not be able to have any settlements there until after it happened. But somehow still seems more practical than some giant space needle injecting uranium into the core.
- We could lay a network of wires on the surface of the planet and use a combination of nuclear and solar energy to create a magnetic field that acts like earth's does for us. Okay -- that actually sounds remotely plausible. This is where I was going to stop. That would be cool. I can totally imagine that.
Humans are generally subject to a pattern of thought called "satisficing." Once we have an idea that is acceptable, it becomes a lot harder to question the idea or to seek better alternatives. I'm no exception in that vulnerability. I thought I had a reasonably clever solution that might be hard but actually possible.
I went to get a link on how the ancient martian magnetic field stabilized its atmosphere and found this: NASA proposes a magnetic shield to protect Mars' atmosphere. In short, this is a proposal to provide a magnetic shield by parking a magnetic dipole shield at the Mars L1 Lagrange Point.
Okay. Mind blown. That is amazing.
2 comments:
My knee-jerk reaction was that it would be much harder to generate a protective magnetic field than it would be to build huge greenhouses. But the more I think about it, the more I wonder whether your idea might be plausible at the planetary scale. It would be interesting to run some numbers.
Greenhouses need to keep out harmful radiation for humans and let in beneficial radiation for plants - not impossible, but maybe a bit tricky. And they are vulnerable to puncture -- a real issue at planetary scale, I think. If you sit in the surface of a gravity well and have no atmosphere to burn up meteorites, you need to do some careful engineering. At large scale, I think greenhouses may be less practical than generally imagined. But I have not done the numbers there, either. Mostly I was just impressed by the wonderful creativity of the idea of parking a shield at L1.
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