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Terraforming - Human Destiny or Hubris?
jangobongo writes "Space.com has a thought-provoking article written by Dave Brody for Ad Astra Magazine about the practical and ethical aspects of terraforming other planets. Mars is currently the focus of most terraforming debates, but the author's conclusion is: 'What works is what takes the least work: [terraform] asteroid/comet resources in near Earth orbits... Humanity would get lots and lots of cheap, free-floating, scalable, designer settlements in interesting, useful orbits.' These would then become stepping stones to other planets in our solar system and beyond."
Ad Astra was originally a space settlement magazine when the L5 Society merged with the National Space Society on condition that the emphasis on space settlement remain its ultimate priority.
What is the difference between a space settlement and a terraformed planet, you might ask?
The fact that you need to ask is evidence that the foundation of the National Space Society was long ago abrogated for more "fashionable" pursuits, such as those promoted by hucksters like Zubrin.
One of the better answers to that question is in Mike Combs' Space Settlement FAQ
Since the Ad Astrans have had the unmitigated chutzpah to quote the originator of the space settlement idea without talking about actual space settlement -- pretending the idea simply doesn't exist, I'm going to provide an appropriate rebuttal: The entirety of Mr. Combs' FAQ.
What is space settlement?
Space settlement is the concept of colonizing space by using extraterrestrial resources to construct artificial, closed-ecology habitats in orbit.
What is a space habitat?
A space habitat would be a pressurized sphere, cylinder, or torus (donut shape), rotating on its axis so that centrifugal force serves as an artificial gravity. The interior is landscaped with soil, water, and vegetation. Sunlight would be gathered by mirrors and reflected into the interior of the habitat through windows. The goal is to create as Earth-like an environment as possible.
How is space settlement different from any of the other space colonization proposals?
Most thinking regarding human expansion into space has focused on the settling of the surfaces of other planets, sometimes after modifying their environments to make them more Earth-like (called terraforming). The space settlement concept maintains that planets are not the most ideal location for human colonies beyond the Earth.
Aren't we going to terraform Mars or Venus?
Terraforming is a long-term project requiring technology significantly advanced over what we have today. Even terraforming advocates admit it would take a minimum of 200 years to modify Mars to the stage where even simple anaerobic microorganisms and algae can survive. [Ref: Terraforming: Engineering Planetary Environments, Martyn J. Fogg, SAE Press 1995.] Space habitats, on the other hand, can be built with today's technology, and would be homes in space which people initiating the program could move into within their lifetimes.
Interstellar travel may someday become possible, but we have no guarantee that Earth-like planets will be as plentiful in the Milky Way galaxy as they have been in Hollywood, CA.
What advantages would orbital settlements have over a colony built on another planet?
Sunlight also drives the life-support system of the habitat, so the day/night cycle can be set to whatever is convenient. Compare this to the moon, where there is 14 days of continuous daylight, and then a 14-day-long night. Here, some alternate energy source would probably have to be used half the time.
Seastead this.
Would not many hundreds of metres of iron absorb the radiation?
Besides, it's a lot easier to picture living on Mars. The landscape has such an Earthlike feel to it. It's easy to picture a city off in the distance haze, sagebrush growing scattered across the landscape, etc.
Even if you can't get an O2 atmosphere, just increasing the atmospheric density to a sizable portion of our own would be a huge benefit. You wouldn't need pressure suits (only rebreathers and, depending on temperature and atmospheric composition, possibly unpressurized skin-protecting layers). The atmosphere would do a good job shielding you from radiation, the climate would be more moderate, and if you had to protect crops from the atmosphere still, the greenhouses would be much lighter if you didn't have to have them pressurized.
Did he just go crazy and fall asleep?
Plants like cues from gravity as well, although they don't usually require them and are easier to adapt.
There are NO plants that will grow without gravity. Not one. Technologists are working on creating strains that can survive and grow, but have not yet met with success.
-1 Uncomfortable Truth
Clearly, it's not as easy as just increasing the atmospheric density on Mars, but that would certainly be a start.
It will only really work with the tougher Iron asteroids, though, the weaker "rubble piles" won't work.
And big ones, too. Smaller ones will have far too much Coriolis force and too much of a vertical gravity gradient for people not to get nauseous, especially if you want tall buildings. Tens of kilometers is probably the minimum.
And, of course, the bigger you get, the bigger a job hollowing it out is.
Our moon is easier to get to, and has a lower gravity. So it's easier to "fly" on the moon. Also, since the moon has no atmosphere, there wouldn't be any wind loads on the structure. It would need a blanket of dirt to protect against very small meteorites, but then again, the dirt wouldn't impose much of a load.
I think it would be cool, too. I just wanted to point out that it is easier to do on the moon, and cheaper to get there, and cheaper to build to the dome.