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Orbital Resort to Launch by 2010
Neil Halelamien writes "Popular Science has a cover feature on self-made billionaire and space enthusiast Robert Bigelow (who's been mentioned before on Slashdot). The article has new info on Bigelow's plans to launch a 'CSS Skywalker' orbital resort by 2010 and sell space habitats to others, such as scientists, manufacturers, Hollywood producers, and countries. The habitats will be made of inflatable modules with multilayered kevlar-like walls. A prototype habitat will be launching on a SpaceX Falcon V next year. To help ensure cost-effective access to the station, Bigelow is also running the $50 million America's Space Prize. In the long run, he plans to use the modules as the basis for space yachts and moon cruisers."
The print article has a nice cutaway drawing of the "18-inch-thick shield of alternating woven graphite composite and foam to protect against orbital debris." Apparently, this layered foam shield is more protective than "aluminum three inches thick" and "no rigid spacecraft design can match this performance." (from the text of the article) It sounds like NASA's decision not to use the TransHab inflatable design was politically motivated and the program was axed before it could actually be tested.
MicroMeteoroid and Orbital Debris (MMOD) shield - "Composed of five layers of graphite-fiber composites separated by foam spacers, the MMOD is the outermost section of Nautilus's hull. Schneider's crew's original TransHab design had more stopping power than did aluminum three inches thick. Ground-testing of Bigelow's MMOD has shown that it can stop impacts by 5/8-inch-diameter aluminum pellets fired at it at 6.4 kilometers a second, several times as fast as a rifle bullet. No rigid spacecraft design can match this performance, and it's one of the reasons Nautilus has an expected life span of at least 15 years."
Here's the guff:
t en t/interactive/space/iss/1998/980824.html
... they begin to realize, 'Hey, this isn't a bad thing at all,'" de la Fuente says.
http://www.chron.com/cgi-bin/auth/story.mpl/con
"Never mind that all this luxury would be in a balloon that would be in an Earth orbit littered with dangerous space junk.
The 1-foot-thick shell would be "bulletproof" in space, de la Fuente says. The 17 or so layers would be made of ceramic fabric, polyurethane foam, polymer film and Kevlar, a tough material used in police vests, and be better than metal.
"This is very different from a child's balloon," de la Fuente explains as he shows off samples of padding. "This is much more like a football. You can drive a nail into a football and it doesn't just pop."
Like a football, the 40-foot-long, 27-foot-diameter Transhab would have a bladder system that holds in the air. The shell encompassing Transhab would have three bladders, in fact, for redundancy.
Outside these thin-film bladders would be Kevlar webbing and then sheets of ceramic fabric, each separated by 3 inches of foam. It's this ceramic, called Nextel, that would protect against micrometeoroids and other orbital clutter zooming by at tens of thousands mph.
In ground tests, aluminum marble-sized balls fired into the Transhab padding at orbital speed were pulverized by the outer ceramic layers before reaching the air-containing bladders.
Even skeptics were impressed.
"Once they see our micrometeoroid and orbital debris shots
"You also have to remember that the aluminum (space station) module is a balloon, too. Any pressure vessel is truly a balloon. Just because it's made out of aluminum you still get the same pressure stresses."
Indeed, when identical balls were shot at 1-1/2-inch-thick aluminum plates, 3-inch-wide craters emerged and the shock waves ripped chunks of metal off the back of the plates. "
I am a mechanical engineering student at Texas A&M and have had Bill Schnieder (one of the former NASA engineers mentioned) as a professor. He hold a patent on inflatable space habitats, and was deeply involved in TransHab. I did a lot of work with inflatable space habitats while I was Dr. Scnieder's student for a year long senior design class. This is some amazing technology.
An inflatable structure makes complete sense. For starters, it works around one of the major design constraints imposed by rocket launch, payload diameter. This enables you to create much higher working volumes inside your spacecraft. For a space hotel this is definitely a Good Thing.
IIRC, Micrometeorite protection is better than on the current ISS modules. It works in a fundamentally different way. Several layers of a tough fiber are separated by expanding foam. When a projectile hits a layer of fibers, the fibers are so strong and hard that even though they break, they also break the projectile into smaller pieces. This dissipates a lot of energy. These pieces then move apart from each other and continue through the foam layer, hitting the next layer of fibers, but this time its several smaller, lower energy pieces each hitting a different part of the fabric, and being broken up again. This is ingenious, you essentially "divide and conquer" the incoming impact energy until your "bulletproof" fiber stop the projectile fragments completely.
The vessel cannot (ok, should not) pop like a balloon. The bladder layer is made up of a very tough polymer that is not very notch sensitive. A hole does not mean a critical failure is immanent. The plastic will probably yield slightly around the hole, but should not tear catastrophically. This leaves a hole about the size of the debris, and a slow leak that can be repaired. The bladder is supported by a network of high strength straps that actually carry the load. Think about putting a huge garbage bag of water in a hammock and then filling it with water. Normally, the bag might break under the weight of the water, but the netting of the hammock is carrying the structural load, while the bag is primarily containing the fluid. Poke it with a pin and you would get a leak. Same principle with the inflatable space habitat.
As far as radiation goes, semicrystaline polyethylene is actually pretty good at stopping the lower energy stuff. It would be comparable to what was on the lunar lander, and what is available for spacesuits. Add water, like they seem to suggest, and it can only get better. I would still probably want to hide from a solar storm, though.
Also I think by the phrase "User Installable" the operator is meant, not the guest.
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.