Centrifugal Spaceships

Back when we still thought we were going to spend the next 50 years exploring space, one of the popular ideas was to implement artificial gravity by putting passengers and crew into a big centrifuge.  Wernher von Braun, Chesley Bonestell, Arthur C Clarke and many others included giant, rotating space stations as part of their imagery.   These guys understood that lack of gravity was a real problem and thought dealing with that was critically important.  As real experience with humans in space as been accumulated, the consequences of "microgravity" have been recognized to be even more serious than they'd feared, leading to bone loss and other problems.  So why is it that we haven't built spinning space stations?

The reason is that there turned out to be lots of other problems that were equally, or maybe even more serious.  Simply getting stuff up there has proven incredibly challenging, and the economics have worked out that many, small, unmanned satellites provide a much better return than putting humans up there.  Secondly, the reality turned out to be that the political advantage gained by the space race was fairly limited to "beating the Russians".  Once that was accomplished, there was really very little popular support for the space race.  So there was little support for big ideas like the space station in the image above (by Bonestell), which inspired Arthur C Clarke and Stanley Kubrick in their movie 2001: a Space Odyssey.  The space station we've actually got, 12 years after 2001, has a pressurized volume of 29,600 cubic feet--about what 3700 square feet of building have.  Much of this is filled with equipment, so the living space is really no more than that of a moderate family house.

If all that space were organized into a ring like the one above-12 feet wide by 8 feet high, the ring would be a mere 64 feet in diameter.  To spin it fast enough to make a 1/6th G (lunar gravity) would take 7RPM, or fast enough to make 1 G, it would take 17RPMs.  Ridiculously fast, and not really practical if you're trying to take a look outside or dock a spaceship.  To get it down to the stately speeds we saw in "2001", it would have to be a half mile or more in diameter.  At that size, lunar gravity can be simulated with just one RPM.  The centrifuge inside the "Discovery" spaceship, where we first met movie astronaut Frank Poole jogging, was about 50 feet in diameter, so it would have to spin even faster.  I'm sure for really long trips, like the one they're on in the movie, space ships would have to contain such centrifuges.   I think that's about the smallest practical human centrifuge though.    Eventually, we'll have big, kilometer diameter or bigger space stations, and I have great hope for O'Neill Cylinders some day in the future.  But not for a while yet.