Even More Random Thoughts About Sundancer

A commenter earlier brought up an interesting thought that’s been bugging me for a while. Bigelow is trying to build his 3-person Sundancer module to be light enough to launch on either a bare-bones Atlas V, or a single-stick Falcon IX (or a Soyuz for that matter). However, he’s not going to actually ramp up the available capacity to 9 people until 2012 when Nautilus is on-line. Now, this might actually make sense, if nobody is able to field a manned commercial vehicle with high enough flight rate to keep Sundancer busy until then. However, if someone is able to come up with a passenger transportation solution, it might be better for Bigelow to just crank out a few more Sundancer modules while he works on finishing up development on Nautilus. That way he can ramp up demand more smoothly, and benefit from higher flight rates (and hence lower ticket prices and more demand for his modules) sooner rather than later.

Sundancer is also conveniently small enough that it’d probably make sense to have more than one station in more than one orbit/inclination. A Sundancer module for instance might make a good core for a transportation node/fuel depot. By having the fuel depot man-tended, all of the Autonomous Rendezvous and Docking issues, as well as the automatic propellant feed coupling issues go away, as you can use man-in-the-loop controls to simplify the former, and could just manually connect couplings for the latter. Or you could see having one or two Sundancer modules used as free-flyers for microgravity research/production. Once every couple of weeks, a new supply ship would get there, tend the station, load and unload new experiments or raw materials/processed materials, perform any preventative maintenance needed, get the experiments started again (and do any debugging needed) and then close it back off and head home. Or if you had such a free-flyer in a close formation with a manned Sundancer station, you could ferry back and forth to the unmanned free-flyer if problems cropped up, without having to have people on-board continuously, which tends to greatly degrade the microgravity environment (us humans are clumsy louts).

Other uses could be like I mentioned previously, as “mission modules” for use with commercial capsules to allow for long-duration spaceflight. Combine this with a refueled upper stage of some sort (either a K-1 like I’ve discussed, or a Falcon IX upper stage like I talked about way back, or a refueled Centaur like LM has discussed), and you could very well have commercial translunar missions before the Block I CEV is even in service.

One other point I ought to discuss. As I mentioned in the other post (and previously in my writeup of my Bigelow visit):

While in there, I was able to pick the brain a bit of the engineer who was giving us the tour. I had been curious to find out if Bigelow was interested in doing subscale versions of the module for potential use in lunar transfer vehicles or other applications. The answer I was given was that Bigelow would probably be willing to work out some sort of a deal if there was sufficient interest. I also asked him what the current plans were for launching the station, since the reported weight of 50,000lbs puts it at the upper end of what current ELVs can deliver to orbit. He mentioned that they were looking at several options, including launching all at once on a Delta IV Heavy, or maybe a Proton, or even The Stick if it gets developed. He also mentioned that if those didn’t pan out, or if a lighter lift but more affordable booster was on the market, that they might launch it in several pieces and fit it out on orbit. As it is, there’s a decent amount of on-orbit fitting out anyhow for an inflatable module, so this isn’t as big of a hassle. A lot of the quoted weight is probably in the water bags used for radiation control, and in other internal pieces, so maybe flying it on three or four Falcon Vs might be possible. He didn’t state what the minimum mass they could break it down into was though.

One thing that means is that if Nautlius could be launched partially loaded, and then the rest of the gear brought up and installed on a second flight (possibly halving the required minimum launch weight), the same may hold true of Sundancer as well. Which means that it could possibly be launched mostly empty on a K-1 (if they become available), and then fitted out on a subsequent flight. Sundancer is also small enough that if you really can launch the thing empty, and then fit it out with subsequent flights, that makes using it as a lunar surface module a lot easier. Having a commercial lunar lander that can place 10klb on the surface or even 20klb is going to be far easier than a 45klb cargo lander.

As an old Role-Playing Game manual once said “the potential uses are limited only by the heights of your creativity, or the depths of your neurological disorders.”

Anyway, I think that although Sundancer is seen by Bigelow as a short of near-term solution to get some sort of destination up there, to start the ball rolling, I think that this design may very well have far more potential than that.

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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7 Responses to Even More Random Thoughts About Sundancer

  1. Josh Gigantino says:

    SunDancer sounds a lot like an “American FGB”. If it’s a one-off vehicle, someone else will still have to build that kind of craft eventually. It’s a design that simply works: propulsion, power and life support in one package with crew berths and controls. It’s the big piece of orbital infrastructure that would be missing for Nautilus. SunDancer as described will make a good “construction shack” for outfitting the much larger Nautilus modules. If SunDancer is a success, I can’t imagine Bigelow not marketting them.

    It probably goes without saying, but Nautilus + Sundancer is a complete space station solution.

    I haven’t seen any pics of Sundancer, does it have a Node or single hatches at bow and stern?


  2. tankmodeler says:

    If a good portion of the Sundancer/Nautilus mass is, indeed, water, then if the issues with orbital refueling have been solved, then it works for water as well. If refueling hasn’t been sorted out, water makes a nice safe liquid to practice with. Lets face it, if you mess up, you lose your cargo (or parts of it) but the rest of the implications are pretty benign.

    I also agree that the size of such a module really does lend itself to a lot of potential uses. L1 depots, cislunar taxis, experimental huts for really risky stuff, emergency shacks in case something goes wrong at the station or a regularly visited orbital location. The uses are pretty endless.

    I’ll take two, please…

  3. Big D says:

    What’s the benefit of having multiple stations in different orbits? If 40 is as low as Bigelow is going to go–unless he changes his mind and puts another one in equatorial orbit–then why shouldn’t everything be there?

    As you mentioned, independent modules that you don’t want docked with the main station because they’re too sensitive (experiments) or dangerous (fuel depots), you can place a few hundred yards away, and be able to maintain them without requiring a second set of crew.

    That said, I’m not calling for Bigelow to move to ISS orbit–that’s just inefficient. And if launch sites like Kwaj later take off and make equatorial stations reliable, it’d make sense to start putting everything there instead of at 40–but I’d think you’d still want your modules docked or nearby to each other, it just gives you economies of scale and failure options.

  4. Jon Goff says:

    Big D,
    What’s the benefit of having multiple stations in different orbits?

    Well, basically orbital dynamics. Multiple smaller stations in their own orbits provide more frequent launch opportunities to more launch sites. And all sorts of other subtle details.

    Of course, it may also be my visceral “anti-monoculture” twitch kicking in. I like to assume that the future is going to be one where there’s enough demand for orbital facilities to justify more than just one.


  5. Jon Goff says:

    The water in the bigelow modules is IIRC in the form of bags that are velcroed or otherwise attached to the inside walls. So, they’re in a form where “propellant transfer” is particularly easy–and can be done in a shirt-sleeve environment to.


  6. ザイツェヴ says:

    I wonder if Nautilus can be made spinning relatively slowly along its long axis (to permit docking) and would anything good result from doing so — I mean settling of liquids.

  7. tankmodeler says:


    >>The water in the bigelow modules is IIRC in the form of bags …

    This makes a lot of sense if you are going to transfer the bags manually and are content with them lining the inside of your habitat.

    Would it not make more sense to inflate a double walled habitat and then fill the space between the walls with water by robotic fluid transfer? Now I don’t mean “more sense” right now as the bags are certainly much lower risk, and can be packaged and installed by any number of flights, but I mean for further development, a Mk II SunDancer. If you wanted a more robust orbiting habitat, docking a water tanker craft to the SunDancer and then filling a series of cavities around the circumference would give you a pretty structurally rigid environmental envelope (let the water freeze through application of interior insulation and exterior shading) and free up both the interior and exterior surfaces for mounting hardware to enhance the viability and usefulness of the habitat.

    Us design engineers are never satisfied with things the way they are…


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