21 thoughts on “An Inflatable Space Station”

  1. It’s very telling that a private company can take technology that has been languishing in NASA labs for years and actually apply it.

    Rand,you know damn good and well that is untrue. Transhab never “languished” at NASA; it was under very active development right up until the point where Congress banned NASA from continuing (NASA Authorization Act of 2000, section 127). Bigelow acquired the license for Transhab in 2003.

  2. Nemo,

    I think that is pretty much what Rand meant. NASA may want to do various things, but, if they aren’t given the authorization or money to do it, it won’t happen. The technology developed at NASA for Transhab was going no where (it was “languishing”) until Bigelow licensed it.

    That was a bold and (possibly) precedent setting move on his part. Hopefully, Bigelow will be successful and make a profit on it. His work with that technology has clearly raised the TRL on it enough to that we will be seeing more inflatables in space.

  3. I’m wondering how they plan to store the hydrogen. It tends to be a very explosive Houdini. If the tank is inside the habitat, wouldn’t it tend to accumulate in the habitat outside its tank?

  4. It does seem a little silly to use electricity to turn water into hydrogen and oxygen (not particularly efficient and difficult to store) for use in a thruster instead of using a higher ISP electric thruster using water directly. Although a H2/O2 engine does give robust thrust on demand and allows variable O2 use making it perhaps easier to maintain on board O2 levels.

    I note this portable water purifier that does 1000kg/day for around 1kW which only costs a few thousand:
    http://www.optimalfunctioning.com/science/slingshot-portable-water-purifier-dean-kamen.html

  5. The idea that Bigelow’s habitats have anything to do with Transhab anymore is an urban myth. The only thing Bigelow got from Transhab was a list of things not to do.

  6. It’s a nice accomplishment but let’s not …

    (puts on sunglasses)

    … blow it out of proportion.

    YEEEEEAAAAHHHHHH

  8. The idea that Bigelow’s habitats have anything to do with Transhab anymore is an urban myth. The only thing Bigelow got from Transhab was a list of things not to do.

    You have no idea what you are talking about.

  10. I do not know, I think Bigelow has held on to some of the what not to do from Transhab – like trying to make a typical NASA all in one, one size fits all, inflatable space station instead of modularizing it to more versatile inflatable shells, life support systems, storage, station keeping, and what not (a modular approach can also go much bigger and/or be able to also utilize smaller launch vehicles).

    They have made their life difficult with having to inflate around a solid core and they do not actually gain that much extra volume from inflating (something like only ~3:1 from memory). A three stage telescoping rigid habitat could do as well.

    Bigelow are not exactly taking full advantage of what inflatable systems enable, perhaps even hardly worth the effort at this small an expansion ratio. But that is the way it was originally designed at NASA so it must be right…

  11. Pete, at a glance, I’m not confident in your criticism. For example, developing a modular system of station components seems illogical given the absence of a proven market of some volume. They can always modularize later. Second, a solid core helps in reducing vibration and oscillation of the station, especially if it is part of a larger structure. And it provides a ready platform for attaching internal equipment and infrastructure.

    A telescoping structure has more seams and structural complexity than a corresponding inflatable structure would. Also, the telescoping structure would lengthen, not expand widthwise (which is how a solid core Bigelow module expands). And finally, a 3:1 expansion ratio with all the expansion widthwise still means that you get a station component roughly 70% wider than you’d otherwise get.

    For example, the ISS modules launched by the Space Shuttle were roughly 40% wider (5.5 meters compared to 4 meters, IIRC) than could fit in a EELV like the Atlas V or the Delta IV Medium. While there may be other problems with making the ISS out of inflatable modules with an expansion radius similar to Bigelow’s stations, it’s worth noting that the key reason the Shuttle was required was because of the volume of the modules (some capability for space walks and manipulation of large objects, being a distant second advantage). With inflatable structures, you could launch a replacement station of comparable volume using commercial launch.

    The point here is that even with the “low” expansion ratio, this technology significantly increases the size of structures that can be launched.

  12. Modularization is also about development by parts – so that one does not have to redesign the entire habitat merely to fix one little bug. The transhab design does not appear to be well designed for ease of development – it is not particularly flexible, an all or nothing design.

    Perhaps the core has some rigidity advantages, but it kind of defeats the benefit of an inflatable design to add such weight and structure. For example, there are no internal spaces larger than what a rigid habitat launched on the same rocket would have.

    I am a strong supporter of inflated habits, but I am of the opinion that one should take full advantage of their benefits, do not design them as if they were a rigid habitat module – go big. By my estimates the inflated structure is on the order of 10% of the Bigelow habitat mass. For the same launch mass one could build one with five times the volume (more volume than the ISS) but that only supported half as many people – most of the mass scales with people number, not volume (actually might do better than this, shielding and insulation scales with surface area not volume).

    Volume is cheap, so why skimp on it?

  13. Pete,
    I had a buddy when I was in HS, who had an inflatable habit. He called her Susie!!

  14. How about a design change – make the walls the floor, spin the craft on its longitudinal axis for artificial gravity. Didn’t these people watch 2001?

    And make sure the pod bay door controls aren’t hooked in to the computer.

  15. I think one needs to be around 1rpm to avoid nausea from coriolis forces, inferring about 1.8km in diameter. Perhaps use a 1.8km tether between two or more habitats with an elevator and zero gravity hub station.

  16. Pete:

    If memory serves;

    Most (98%) people will be fine at 1 rpm or less

    About 60 to 70% adapt to 2 rpm or less

    Most people (98%) do not do well above 3 rpm

    This was derived from studies spinning people here on Earth. Nobody has done studies spinning a large structure (>100 m in diameter), people may adapt better to larger structures spinning as the difference in force from the top of their head to the bottom of their feet may be less causing less discomfort.

  18. It’s very telling that a private company can take technology that has been languishing in NASA labs for years and actually apply it.

    I wonder if there are any other hidden gems that could be commercialised. This is potentially a very useful political argument.

  19. Didn’t one NASA center (JSC?) develop a very efficient system for assembling large deployable structures on orbit?

  20. Generally, Martijn, you can take any piece of NASA technology, run it through a venture capital R&D mill, and figure out how to make it operate better, cheaper, and more reliably simply because you are finally engaging the motivational centers of those who are working on the technology.

  21. I believe that when the French first postulated an inflatable ring, back in the ’60’s, they determined that it would have to be roughly 150 meters across to obviate the difference in apparent gravity between head and foot.

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