Wednesday, May 09, 2007

Bigelow Technology

Wow, this post has been sitting in my edit queue since last September. I think it's about time it saw the light of day. Jon Goff at Selenian Boondocks is once again on a roll with his Random Thoughts posts, and one of them actually hits pretty close to an idea that I've been considering for a while now. I hope to take some inspiration from Jon and try to post my half-baked ideas more often.

For some time now I've been contemplating alternative uses for Bigelow's habitats, as has Jon Goff (here and here). Jon mentions that there are many potential uses for the half-scale version, particularly when considering habitable structures that you want to move somewhere besides LEO. If I'm interpreting Jon correctly, he's advocating something similar to what I've come to think of as the Conestoga wagon of spacecraft. For the foreseeable future, this is probably going to be the easiest way to assemble a spacecraft off-Earth and I sincerely hope that Mr. Bigelow considers offering the Sundancer, or similarly sized module for such applications.

So, let's review what we know about Bigelow's plans. We'll start with some of the obvious applications for the habitat modules, for which Mr. Bigelow has provided some hints. In addition to the self-contained habitation modules (Sundancer and BA330) for use in LEO, he has also talked about assembling a lunar base at the L1 point, and then landing the whole thing at once on the lunar surface. Habitat modules for a base on Mars (or Phobos) would also not be that much of a stretch to imagine. The original Transhab, upon which the current modules are based, were designed to serve as crew habitats for a Mars-bound space craft. So, I wouldn't be surprised if the BA330, or a derivative thereof, eventually becomes the core of a reusable spacecraft for facilitating inner solar system exploration. A cislunar or cismartian cycler would be a useful application. However, in the near term, we would probably be more likely to see these modules being used as disposable service modules for extended manned missions beyond LEO (Moon, Mars, asteroids, etc.)

Mr. Bigelow has also recently stated that he intends to start trying to attract commercial interests as well as foreign governments as potential clients for leasing space aboard his habitats. The quoted lease rates seem very reasonable and could significantly lower the barrier to entry for parties wishing to conduct commercial activities in space. If he is successful, then this will mark a major turning point in the history of space exploration and development. This is the kind of reimagining of the future that we need to see more often.

As for myself, I find that the applications I tend to imagine generally fall into one of two categories: what can you do with prefabricated modules (or slightly modified variations), and what could you do with the materials and assembly techniques that are currently being developed to manufacture these modules.

Some time ago, I remember reading the patent granted to Bigelow Aerospace for the inflatable satellite bus and I began thinking about the types of payloads that one might integrate with a Bigelow habitat that would (a) benefit from the presence of a human crew, and (b) make the most use out of having access to both a shirt-sleeve environment and ready access to a perfect vacuum and/or microgravity environment. I came up with several possibilities, but the one I found most interesting was for an advanced propulsion laboratory.

Consider, if you will, installing a VASIMR engine inside of a Sundancer or BA-330. These modules would provide an ideal laboratory environment in which to develop and test the rocket design. If you've ever seen pictures of the VASIMR experimental setup, you realize that most of that structure is the vacuum chamber. The actual rocket is quite small by comparison. The entire structure could be made to fit inside of a Sundancer module with room to spare. Such propulsion modules could even eventually be used as components of larger spacecraft. Imagine being able to work on a spacecraft's engines without having to perform a risky EVA.

Any number of experimental testbed platforms could be constructed in a similar manner. (Hmmm... a crewed Hubble Space Telescope...). Even if the platform is not crewed full time, the ability to make repairs and upgrades in a shirt sleeve environment sounds very appealing to me.

It also occurs to me that the materials and technologies being developed at Bigelow Aerospace may have even more far reaching applications. For example, consider a future in which the material used to construct the various layers of the outer hull of the Bigelow habitats is delivered to orbit in bulk where it can then be assembled into a hull for a spacecraft or spacestation in essentially any arbitrary configuration. These materials and the hull designs would represent an amazing leap forward in our ability to build structures in space. Spacecraft and spacestation designs need no longer be confined to TinkerToy-like structures. We would no longer restricted to thinking in terms of aluminum canisters which are restricted in size and shape by the geometry of the payload fairing of their launchers.

Granted, there will need to be alot of research into how to actually do construction of this nature on-orbit, but I'm sure this is something we should be able to figure out within the next ten years. I would hope, though, that once Bigelow has a revenue stream being generated from his first few orbital stations, that he reserve at least one for his own use as an R&D shop.

These techniques will eventually have to be developed if we are ever going to establish a significant off-world presence. Up until now, the dual technical hurdles of delivering suitable construction materials to orbit and assembling them on a large scale have seemed almost insurmountable. Now, for the first time, I can finally begin to see how both of these difficulties may be overcome.

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1 Comments:

Blogger Nyarlathotep said...

I would think the vacuum and shirtsleeve access would be more useful for bulk semiconductor manufacturing.

3:59 AM, June 03, 2007  

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