Mar 12 2009
Thieving Thursday: Space Station Concepts
So, once again it’s thieving Thursday and I was really wondering if I had any comments worthy, you know, of stealing. Between being emotionally devastated on Tuesday and Roxy’s birthday yesterday, I figured my comments had been pretty nondescript. Fortunately for everyone, Habitation Intention gave me my big break. They showed a design submitted for a contest sponsored by NASA and SolidWorks . Clearly the folks at Habitation Intention were taken with the spherical design and the notion that artificial gravity could be brought to bear by spinning it “on it’s X,Y, and Z axis.” I noted that you can really only spin it on one axis and that rotating space stations are really a very old concept (as far as space technology goes). Not that the idea isn’t interesting, or even worth pursuing, but space stuff is rarely as simple as that.
I mentioned a few things that might make this concept challenging to implement, not because they are insurmountable, but because it’s easy to lose sight of different aspects in space. For instance, spinning anything in space adds considerable complexity to a space craft. With all of the mass at the edges (rather than near the center of gravity), just moving around this sphere could really cause substantial oscillations. Also unless you were at just the right place, the gravity gradients would be different and could very well wreak havoc with the inner ear equilibrium, making it perhaps perfect for some and vomit-inducing for others. I suspect that’s one reason previous spinning space stations were generally in a ring as opposed to a sphere (which would be less complicated to control). Docking with a 
spinning spacecraft is challenging and power generation and radiative cooling were not clear to me. Again, this isn’t to say it couldn’t be done, just that there are some complexities that might give one pause. Not that new ideas aren’t good to play with…
Naturally, of course, I went to go see if I could reassure myself that I wasn’t misremembering those early space station concepts and, sure enough, I wasn’t . Actually, I had a great time reading about the many and clever ideas we’ve had in the past (and I say we like I was involved, but they were all before my time), though seeing the potential concepts (one as inexpensive as $100 mil which seems a bargain even by yesteryear’s standards) that came to nothing primarily for politics is a little disheartening. There’s a lovely write-up of Langley’s attempts 
to address space station needs here and another write-up where Marshall touts their own space station history , including Skylab. Astronautix.com (a must for any space history enthusiast) has a wonderful history of the different notions , concepts and plans for space stations the US has contemplated over the years. I’m including a few here from the one-man Mercury based “station” to the huge “Space Base,” even stations that simulated gravity from the inflatable toroid of Von Braun to Langley’s hexagonal spinning self-deploying hexagon.
Fun stuff. Oh, and one more picture from NASA (STS-119, which was delayed yesterday). Isn’t that a cool picture?
I’m glad you stopped by. I did like the Shuttle Moon conjunction. It’s a sight you can see just anywhere.
Fascinating post, thank you! I suppose, since a space station or ship like that would be relatively small, compared to something like the earth, that the gravity difference even from the head to the feet could create a lot of problems, couldn’t it? Or am I way off, on that?
Absolutely gorgeous photo. Just stunning.
Bookish, you’re not way off on that. In fact, it was a very insightful question. When it comes to gravity, the force is relatively straightforward, going fairly uniformly “down”. When you spin something, there is a force that pulls out (reactive centrifugal). In orbit that force and gravity counter each other so the NET force is ~0. Astronauts are subject to gravity - but the net force is zero.
When spinning a space station, there is a potential to use that spinning to simulate a gravitational force on the outside surface of the spun wheel. The wider the wheel, the less rotation needed to get higher force values. The closer you get to the hub, the less the apparent gravity.
However, this spin (and controlling the spin) depends on a controllable center of gravity. Too much mass in the outside or between hub and outside ring, it can readily introduce a wobble as can moving mass around the edge of the ring so it’s not uniform. Wobbles introduce force fluctuations, often in unusual directions and that can really mess with the body’s balance detectors. Anyone’s who’s had a debilitating case of vertigo can tell you the results can be really tough, including nausea, disorientation, etc. You have to be able to control it so that it’s going in one direction reliably and moving in directions that will confuse the body to make this effective.
No small task.
Wow, my moon was were you were, too! So glad you had a picture of it… it reminded me of my own sighting Tuesday night.