Inflatable space stations: do they make sense?

[Sidewinder]

Private Space Station Prototype Hits Orbital Milestone
By Tariq Malik
Senior Editor
posted: 9 May 2008
1:53 am ET

A prototype module for a private space station has passed an orbital milestone after completing its 10,000th trip around the Earth.

Genesis 1, an inflatable module built by the Las Vegas, Nev.-based firm Bigelow Aerospace, passed the 10,000-orbit mark as it nears the beginning of its third year of unmanned operations, its builders announced late Thursday.

Bigelow Aerospace launched Genesis 1 atop a converted intercontinental ballistic missile on July 12, 2006 to test its ability to self-inflate and operate in Earth orbit.

Now, more 660 days later, the spacecraft's exterior cameras have taken some 14,000 images that include snapshots of all seven of Earth's continents. Its solar panels have also continuously powered electrical systems for about 15,840 hours, Bigelow Aerospace officials said.

Led by businessman Robert Bigelow, owner of the Budget Suites of America hotel chain and other enterprises, Bigelow Aerospace followed Genesis 1 with a successor, Genesis 2, in June 2007. That module also continues to function as designed.

With a length of about 14 feet (4.4 meters) and a diameter of 8 feet (2.5 meters), the Genesis modules are one-third scale versions of Bigelow Aerospace's planned BA-330 modules for manned missions.

"Since it was lifted into orbit, Genesis 1 has continued to perform its main mission to test and verify systems to be used in future manned space habitats," Bigelow Aerospace officials said in a statement. "Genesis 1 has traveled the equivalent of more than 270 million miles, which would take it to the Moon and back 1,154 times."

Bigelow Aerospace hopes to begin assembling its first crewed station using its Sundancer module in about 2011.

While 10,000 orbits is a major milestone, Genesis 1 has a long road ahead if it wants to catch up to the International Space Station, which is currently manned by a crew of two Russian cosmonauts and one U.S. astronaut as it circles the Earth. NASA and its international partners plan to launch the lab's largest laboratory, Japan's Kibo module, later this month.

The ISS celebrates its 10th anniversary this year and its oldest component - Russia's Zarya control module - surpassed the 50,000-orbit mark in August 2007 to complete what was then a 1.3 billion-mile (2.3 billion-kilometer) trek. When fully assembled in 2010, the ISS is expected rival a U.S. football field in length, include enough living space as a five-bedroom home and carry a crew of six astronauts.

So someone wants to build an orbital hotel... out of inflatable modules... despite the dangers of radiation, micrometeorites and other space debris (note that these things can travel at three kilometers PER SECOND). So does it make sense to make a space station out of inflatable modules? (I suspect the costs of protective measures, e.g., radiation shields and armor, will eat up whatever savings you'll get from using inflatable modules instead of metal.)

[Superman]

Well, I hear that they're using it for a kids' bouncy house during the off hours. For birthday parties and whatnot.

[Junghalli]

I'm sure if they're already sinking the money into launching a prototype into orbit (which is not cheap: anything in orbit costs thousands of dollars a kilogram at present) they've already considered problems like micrometeorites and radiation in their studies. You don't make a multi-million dollar investment on the basis of something somebody just thought sounded cool. Anyway that's the point of a prototype: to see if it'll work.

If it can work it'll be a rather neat near-term system. It's probably lighter than a conventional module and it's easier to fit inside a small rocket than the big solid modules that are used now. Of course, I'm a big advocate of setting up an asteroid mine, setting up infrastructure to make space stuff in space, and doing away with all this nonsense of dragging everything up from Earth's surface.

[dragon]

If you did any kind of research into the topic you can see from the data that the inflatable craft are just as safe if not more so than the thin hulled ISS.

And actually the inflatable craft is three layers with various chemical bonding compounds in between. When the craft is struck and a hole is made the material between the layers flow in the gap and hardens forming a plug.

As for radiation before the ISS got its upgraded anti radiation material the crew absorbed as much radiation in one day as a person on the planet absorbed in 1 year. At that rate a three month stays turns into 1/10 the risk of a long term smoker. Oh and since the ISS is in a LEO it is mostly protected by the earths magnetic shield. And the new shielding only increased the radiation protection by about 20%.

Now solar radaition is 95% protons and when the protons strike the material. When a proton collides with the material of the craft neutrons are produced. These neutrons upon colliding with a hydrogen nucleus, liberates their energy. Living organisms contain a large amount of hydrogen rich compounds. The effects of this liberation of energy have several determinately side effects.

Now if instead of having a thin metal shield like the ISS you take a triple layer craft like the inflatable ones. If between the first two layers you place a hydrogen rich compound the energy will be released in that layer instead of inside the bodies of the passengers. And since the layer is close to the vacum it is easy to dump the waste heat.

So you can see the inflatable ones are just as safe if not more so the using metal hull. Also since its lighter and smaller at launch time, that means you can build bigger stations and can use the saved wieght to lift other important equipmewnt.

[Broomstick]

I wonder if it would be feasible to spray something onto the exterior of an inflated module to increase strength, shield, or other properties? Sort of a space stucco.

[GrandMasterTerwynn]

So someone wants to build an orbital hotel... out of inflatable modules... despite the dangers of radiation, micrometeorites and other space debris (note that these things can travel at three kilometers PER SECOND). So does it make sense to make a space station out of inflatable modules? (I suspect the costs of protective measures, e.g., radiation shields and armor, will eat up whatever savings you'll get from using inflatable modules instead of metal.)

Do people even think before posting? I have to wonder. I'll echo what's been said before. The ISS has a very thin, extremely lightweight hull. The debris you mention will perforate it just as easily. Most radiation penetrates it fairly easily. As has been mentioned, the inflatable module is self-sealing in the event of such a breach, and it is probably safer against radiation as you can build it with material layers that absorb neutrons, and unlike a metal structure, an inflatable structure wouldn't be as prone to x-rays produced by bremsstrahlung.

The inflatable modules are really quite an achievement, and I'm pleasantly surprised to learn that the prototype has been operational in Earth orbit for nearly two years.

[Drooling Iguana]

The idea of paper spaceships flying to and from inflatable space stations amuses me to end.

[LadyTevar]

I'm suddenly remembering the Tom & Jerry cartoon set on a futuristic space station. At the end, Tom had blasted holes in the space station's ring, causing it to deflate. The cartoon ends with him outside in a spacesuit guarded by men in uniform, patching the all the holes and re-inflating the spacestation with a bicycle-pump.

[MJ12 Commando]

The fact that they're reaching prototype stage is awesome news. Although doesn't the ISS use a honeycomb structure for its walls? IIRC Apollo did to increase protection, and I doubt they've regressed in materials science and complexity since the sixties.

[Coyote]

I have no worries about it being safe, I wonder if "inflatable" is practical for a completely different mission-- if an inflatable ship could be used for the long voyage to Mars. Being cramped into a tiny capsule will drive folks batshit for the, what, 4 months it takes to get there? A nice, "big" (by spaceship terms) inflatable habitation section might be just the thing, but could it withstand the trip?

I'm going to suppose that (1) there is some sort of metal or composite brace to keep it rigid enough for engine burn, and (20 that most of the trip would be on "drift" anyway...

[Dracofrost]

I have no worries about it being safe, I wonder if "inflatable" is practical for a completely different mission-- if an inflatable ship could be used for the long voyage to Mars. Being cramped into a tiny capsule will drive folks batshit for the, what, 4 months it takes to get there? A nice, "big" (by spaceship terms) inflatable habitation section might be just the thing, but could it withstand the trip?

I'm going to suppose that (1) there is some sort of metal or composite brace to keep it rigid enough for engine burn, and (20 that most of the trip would be on "drift" anyway...

If I recall correctly the technology was originally developed by NASA with that specific goal in mind, but for whatever reason they decided to stick with the normal rigid design for the ISS and mostly abandoned inflatables. Which is when Mr. Bigelow bought up the rights or license... gah, damn my fallible memory.

Anyways, it entirely depends on what sort of propulsion you're using. If it's something like a VASIMR or Ion engine the thrust would probably be low enough for the inflatable life section to be self supporting.

[Patrick Degan]

I have no worries about it being safe, I wonder if "inflatable" is practical for a completely different mission-- if an inflatable ship could be used for the long voyage to Mars. Being cramped into a tiny capsule will drive folks batshit for the, what, 4 months it takes to get there? A nice, "big" (by spaceship terms) inflatable habitation section might be just the thing, but could it withstand the trip?

I'm going to suppose that (1) there is some sort of metal or composite brace to keep it rigid enough for engine burn, and (20 that most of the trip would be on "drift" anyway...

Steady acceleration and deceleration should solve most of that problem. It's not as if the ship would experience sudden shifts in vector which would collapse a structure made of thin aluminium sheet over a preassembled framework as much as it presumably would an inflated ship.

What inflatable main sections can provide is, as has been alluded to earlier in this thread, the ability to get them to orbit in a far smaller launch package. Framework members can also be carried separately to orbit and once there the whole thing assembled easily enough. The inflatable modules can be designed to have frame tubing already incorporated along strategic points within the fabric of the module, which can be linked to the external bracing during orbital assembly. That should make the whole thing rigid enough for the trip.

[Kanastrous]

I suspect it's possible to design an inflatable in which the supporting structure is inflatable, too.

Goodyear did some very interesting research and prototyping on inflatable aircraft for the USAF; about the only non-inflatable component was the engine.

[Patrick Degan]

I suspect it's possible to design an inflatable in which the supporting structure is inflatable, too.

Goodyear did some very interesting research and prototyping on inflatable aircraft for the USAF; about the only non-inflatable component was the engine.

Really? That would be an interesting read.

[Broomstick]

I should point out that both zepplins and dirigibles are quite functional inflatable aircraft, as are both hot air and lift gas balloons.

I believe Kanastrous is referring to fixed wing inflatable aircraft. I am aware that there were prototypes, but not much beyond that. I dimly recall something about difficulty in retaining proper internal pressures, but in space that may be less of an issue (although temperature changes will have an effect).

[Kanastrous]

here's what on th' wiki...

http://en.wikipedia.org/wiki/Goodyear_Inflatoplane

[Kanastrous]

I believe Kanastrous is referring to fixed wing inflatable aircraft.

Yes. Silly of me to have somehow forgotten dirigibles, et all!

I am aware that there were prototypes, but not much beyond that. I dimly recall something about difficulty in retaining proper internal pressures, but in space that may be less of an issue (although temperature changes will have an effect).

What I wonder, is what kind of stress that sort of inflated structure can withstand. Would it lend itself to high g-load rocket-type acceleration?

[Resinence]

What I wonder, is what kind of stress that sort of inflated structure can withstand. Would it lend itself to high g-load rocket-type acceleration?

Why must it be inflated at launch? I would think just launching it with a container of compressed air would be much easier.

[Kanastrous]

I mean, what kind of acceleration could it take, in transit from Earth orbit to points further out.

[Patrick Degan]

I mean, what kind of acceleration could it take, in transit from Earth orbit to points further out.

I should think a steady 1g acceleration from orbit would be doable without undue stress on the structure.

[Finagle]

This whole thread reminds me of Larry Niven's books, which made relatively extensive use of inflatable living areas in spacecraft and on planets without breathable atmospheres. In his books there was a type of spacecraft hull which was impervious to practically anything (IIRC it was designed as a single incredibly complex molecule, but essentially it might as well have been magic), but it only came in a few pre-fabricated sizes and shapes. In at least one story (I think it was one of the Beowulf Schaeffer ones) they had an inflatable section outside the indestructible hull in order to provide extra living space during normal operations, and then if things looked like they might get dangerous, they would come back inside the main hull, and deflate the extra section.

I don't really have a point to this post, other than to say that the idea of inflatable spacecraft and space stations just seems to be amazingly cool to me.

[Phantasee]

I saw Genesis 1 flyby last week. It was pretty hard to make out, just a speck of light, but I thought it was kind of neat.

Beats the ISS: I never get a chance to see the damned thing...

[Macunaima]

here's what on th' wiki...

http://en.wikipedia.org/wiki/Goodyear_Inflatoplane

Quite interesting. And the name "Inflatoplane" amuses me to no end.

[Aquatain]

here's what on th' wiki...

http://en.wikipedia.org/wiki/Goodyear_Inflatoplane

Quite interesting. And the name "Inflatoplane" amuses me to no end.

Think of the possibilities.. Strato-Inflato, or just Starflato amongst friends.