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Details On Inflatable Space Modules
Decibel writes "Although it's been mentioned on Slashdot twice now, this article contains more details about Robert T. Bigelow's plan to orbit massive inflatable space habitats, with the first test modules to be launched next year. It also details the $50 million "America's Space Prize", with the objective to "spur development of a low-cost commercial manned orbital vehicle capable of launching 5-7 astronauts at a time to Bigelow inflatable modules by the end of the decade.""
It's kind of cool to see this idea come to fruition. I'm sure that every child has gone through one of those inflatable castles and wondered what it would be like to have an inflatable house. I myself have often wondered if houses on other planets could be constructed in a manner similar to the late Xanadu. Just inflate the basic structure with just high enough PSI to make it rigid, then spray foam all over it. Allow the structure to cure, and you've got yourself air-tight, super-strong walls that can be repaired from pretty much any damage just by spraying more foam!
Something to think about, anyway.
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I'd love to see the "Trojan Condom" logo on that thing. Talk about great product placement.
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Inflatable space modules are all well and good--until The Terrorists(tm) develop a gigantic space pin!
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If (big if) you inflate to sea level air pressure you need to contain 15 psi. Not a big deal. A bike tire can take up to 100 psi, a plastic 2l coke bottle can take over 150 psi. Make the habitat B I G and it will hold a lot of air. If something pops a hole in it, it will take a long time (many minutes) to deflate. Somebody will have to put down their beer, float over to the hole and slap on a peel-n-stick patch.
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With all the needle jokes and condom comparisons one could get the impression that these inflatable modules are less rugged than the aluminium modules now used for the ISS.
This is not the case. They are made out of multiple layers of kevlar (the same stuff that bulletproof vests are made of). In tests with the NASA-designed transhab inflatable module they have proven to be much more resistant to space debris than aluminium hulls.
Also even if a particulary large piece of space debris should punch a hole in one of these modules, they are so big that there would be plenty of time to evacuate them before the pressure drops too much. A long-time station will probably also have a repair kit on board.
Third, the problem of space debris is particulary severe in low earth orbit. But in a higher earth orbit there is much less space debris, and the stuff that is there moves with much lower relative velocities. So from a space debris point of view low earth orbit is the absolute worst case. A station at an Earth/Moon lagrange point or in deep space would need little or no space debris protection.
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I just can't picture one of these space balloons without thinking about one end coming loose, and the whole thing blasting crazily about in space while making a ridiculously load farting noise.
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Did you read my response? A Big Gemini capsule could easily meet the requirements. Especially on the reentry part. All that's needed is a classic epoxy/silicon heat shield, then the parawing for landing. On the ground the heat shield would be peeled off and replaced, the parawing repacked, and the capsule would be ready for relaunch.
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You are thinking that the walls will be like a rubber ballon.
The walls will be thick enough to provide the same level of orbital debris protection as existing space station modules. Remember, the Atlas booster had aluminum ballon fuel tanks -- it would actually collapse if the tanks were empty. When other engineers were suggesting it would never fly, they presurized it and gave them a sledgehammer to try to break the booster.
It rebounded and almost hurt the engineer swinging the hammer.
The instant-fill holes are harder than you'd think. Instant-fill tire stuff is designed to work in an atmosphere that you aren't breathing.
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The only reason why a balloon goes bang when you pop it with a pin is because the rubber rips and the air is violently released. If you put a piece of scotch tape over an inflated balloon and insert a pin you'll see that the balloon didn't pop but there's a hole. The tape reinforced the balloon and kept the rubber from tearing apart.
These inflatable habitats would simply leak air. There wouldn't be any Hollywood gratifying explosions.
Those micrometeoroids piercing the skin isn't too bad for the bubble. Just a small hole. It's the people and equipment inside that will hate getting sprayed with debris. The way they take care of it on space stations is to create bumpers. An outer shell takes the initial impact. The meteoroid punches through, but shatters and vaporizes, spreading in a plume. The second layer then gets to absorb a reduced impact over a greater area. There's more to it, but that's the basics. To protect an inflatable habitate, it might require a double-bubble, like the Zorb http://www.zorb.com/. Inflate the outer bubble at far less than 1 atm and let it take the punctures. Still have to fix the leaks, but they will be far slower. The inner bubble will be unpunctured.
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This could also be used for interplanetary craft.
Imagine launching to Mars. Even if you launch in a tuna can ala Zubrin, it's still pretty confined. If you launch in an un -nflated balloon, accelerate and get pointed at Mars, you can inflate and have twice or three times the living space. As long are you're willing to be confined for a few hours at first, the place could be quite roomy and more people could be sent per trip as long as provisions are increased.
Just a thought.
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Check out this fascinating detailed design for a completely reusable Saturn-V size rocket, powered by a Gas Core Nuclear Reactor engine. The engine emits non-radioactive hydrogen propellant. The rocket described would be able to lift 1000 tons of cargo into orbit and return to a powered landing, for only 5% of today's cost per pound.
I know "nuclear" is still a dirty word, but the gas core reactor design is a completely different approach than a big pile of plutonium. Very promising in terms of power, safety and cost.
It's a long article, 14 parts, but well worth reading. Skip the first 5 or 6 sections if you just want to know how the thing works.