There are two ways to do it without jeapordizing the ISS as a micro-gravity facility
One is to have a spinning centrifuge inside of the ISS. This depends on how tolerant humans are of spinning motions. There are various lines of research that suggest many humans can tolerate up to 30 rpm or more, for at least an hour a day. and quite possibly most could tolerate it given enough time to acclimatize slowly.
We can't know this for sure, because there are many differences between spinning in space and on the Earth. But experimenters working on this have said it's high time we had an experiment in orbit to settle the question.
The way this would work in the ISS is to have a small centrifuge "spinning hammock". It depends on what you use it for - if it's for sleeping and eating, and gentle exercise on your back, then you could have it as small as 2 meters diameter and 2 meters in length, and spin at up to 30 rpm.
Could Spinning Hammocks Keep Astronauts Healthy in Zero g?
There are two possible orientations of the hammock as shown here
They would feel different because one of them you have a horizontal spinning sensation and the other, (right hand one in the picture) more like a tumbling sensation, we might respond to those differently physiologically.
The hammock is actually moving at no faster than a comfortable jogging speed, even at the 30 rpm and full g. So you probably don't need to have any enclosure, except if the astronaut finds it helps with spinning sensation - just a curtain. Make it so that it is easy to stop in case of any obstruction, even accelerated stop e.g. if astronaut puts their hand out.
Anyway - seems certainly can do it for a few minutes, from the out of control Gemini spin, they span very quickly and did get sick but only afterwords and had no acclimatization. People who were sensitive could set it spinning at a very slow rate to start with and as it's just the individual astronaut not the station spinning, then if someone can't tolerate it at all, they don't need to use it.
But for those who can tolerarte it, it might mean they can spend far longer in space without the ill health you get at zero g.
And whether it works or not in that way, it gives us invaluable information about the tolerance of human body to spinning motions and ability to investigate effect of low and full g and any levels in between - so long as there are people who can tolerate the faster spins - which from ground experiments seems very likely.
Sadly, there isn't enough space left inside the ISS now for even a small centrifuge like this it's been filled up with other things. But when adding a new module, e.g. the BEAM inflatable module, if you designed it with this experiment in mind, you could send it to the ISS pretty easily.
I think definitely has to be a human centrifuge, or won't be conclusive. There's the difficulties of sending large primates into space - which I wonder about the ethics also myself, creatures used to lots of space put into a small spaceship - and rats they can't vomit for instance, not a good analogy for humans.
Anyway is high time we did these experiments with humans, and it's easy to stop if there are any problems, most likely dizziness or nausea, and good chance it will actually help, and with the Skylab jogging track is pretty much same situation, and caused no problems for the astronauts, they found it fun as far as can tell.
TETHER OR WHEEL.
The other way to do it is either tether or wheel. The hub can be at zero g - and then just have the tethered sleeping quarters spinning around it. Again this permits sleeping and eating food etc at full g - and then working at zero g.
There's no problem combining artificial gravity for part of a station and zero go for another part using tethers, or wheels (wheel most likely on smaller scale e.g. sleeping torus shaped tube for sleeping in as in Nautilus X). But we need data first before we can design complex hardware. Tether experiments probably best way to do that and Joe Carrol has an ingenious idea for a way to do that on the way to the ISS - he will be talking about this some more on the Space Show towards the end of May.
So far we have no experimental data from space to back this up except a few experiments the Russians did with rats, experience of the Skylab astronauts on the jogging track - and on their moving chair, the uncontrolled spin of one of the Gemini missions - and micro gravity short duration tether with two other Gemini missions.
For more about it:
Ingenious Idea: Soyuz Crew in Tether Spin On Way to ISS - For Artificial Gravity - Almost No Extra Fuel
Can Spinning Habitats Solve Zero g Problem? And Answer Low g Questions?
and the one I've already mentioned
Could Spinning Hammocks Keep Astronauts Healthy in Zero g?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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