Rotating Compartments on Space Stations

[Philippe Lemay]

I know I know, maybe I should pace my threads out a bit more but I just had a sudden thought and I'd love to hear the ideas of some people here.

Do any of you think that the ISS will ever have a compartment that spins to simulate gravity? Or will we have to wait for a new space station, some time down the road (maybe one bigger and better) that will hold such compartments? Might one of the other countries with space ambitions be the first one to reach this goal? Like China or India perhaps.

Please, discuss.

(Personally I hope they try something with tethers and inflatable modules on the ISS first.)

[Jens]

The ISS is not going to have any more major items installed on it, so the answer is no. A future space station might, however. The only question now about the ISS is how long it will be funded/used.

[Philippe Lemay]

Well I still hope the ISS lasts beyond that 2015 date people have been throwing around. I'm anxious to see a big spinning something on a space station, but not eager enough to vote sending our main platform down early.

But if we do take too long, then it could indeed be India or China that get the first rotator.

[Middenrat]

I heard a lot of practical engineering issues make such an inclusion undesirable, so perhaps there'll always be another solution to the problem which comes cheaper and safer.

[Philippe Lemay]

Eh.. more practical than a spinning compartment? Honestly I don't know of any other way to simulate gravity in a real-life setting. Aside for accelerating continuously at a pretty high rate, but that seems even harder.

I'm very curious, what would this other solution involve?

[Glom]

There was the Centrifuge Accomodation Module. But that was snipped like a vasectomy patient.

[Noclevername]

I heard a lot of practical engineering issues make such an inclusion undesirable, so perhaps there'll always be another solution to the problem which comes cheaper and safer.

I don't know where you heard that, but it's really the only option for long-term human survival in space. So, it may have engineering concerns that make it difficult (as almost everything to do with space has), but never undesirable.

[Philippe Lemay]

Yea, Centrifuge, spinning, rotation, it's all the same trick. Making a compartment of the station (or sometimes the whole station) turn on itself.

I've looked into artificial gravity concepts and let me tell you... the prospect is even less hopeful than FTL (or just about as bad). I doubt we will come up with anything like gravity plating for several thousand years.

So... let stick to spin. What I really want to know is, how long till we start seeing it brought into use. We'll have to see it on a space station for it to act as a prototype, because they'll have to test it before they put it on any kind of Mars spacecraft.

[Hornblower]

As I see it, the engineering challenge would be airtight bearings between a spinning main body and a nonspinning docking module, along with electrical connections with the solar panels.

[Ara Pacis]

I've looked into artificial gravity concepts and let me tell you... the prospect is even less hopeful than FTL (or just about as bad). I doubt we will come up with anything like gravity plating for several thousand years.

I think we'll have a good, solid theoretical explanation for quantum gravity within a thousand years. That will either give us a real possible method or rule it out entirely.

[Ara Pacis]

As I see it, the engineering challenge would be airtight bearings between a spinning main body and a nonspinning docking module, along with electrical connections with the solar panels.

Then don't make a station that needs rotating airtight bearings. Electrical connections might use rolling contacts on rails or touchless induction.

[sirius0]

It will need to be of substantial size or be able to reconfigure it's COM using fluids to compensate for people and other objects moving around. You see when an object spins in a zero or near zero gravity environment then it will spin around it's COM. And if this is allowed to vary substantially due to people movements then there will be all sorts on engineering isues. However It would be a good way to store energy too. A solar powered motor/flywheel/re-generator energy storage and recovery unit.

[IsaacKuo]

What I really want to know is, how long till we start seeing it brought into use.

It's not clear. Certainly you're not going to see a rotating "compartment" any time soon. The required radius of rotation may be on the order of hundreds of meters, so the only thing plausible in the near term is a crew module on the end of a long tether/pole.

We'll have to see it on a space station for it to act as a prototype, because they'll have to test it before they put it on any kind of Mars spacecraft.

I wouldn't be too sure about that. That would be a lot of extra expense for hardly any return in knowledge.

[AlexInOklahoma]

There was the Centrifuge Accomodation Module. But that was snipped like a vasectomy patient.

And was only big enough to 'accommodate' smallish-size specimens (up to ~rat-size). Not quite what the OP was speaking of, I think - but close. The research would have been good to have to prove/disprove the effects long-term on organisms, for sure (!!) It seems that VSE/Cx got more more importance than CAM (see pg4 http://www.fas.org/sgp/crs/space/RL33568.pdf )

http://www.spaceref.com/iss/elements/cam.html

It now sits outside, looking forlorn and forgotten, in a parking lot of Tsukuba Space Center, in Japan. (sigh)

I bet that there won't be (large) 'rotating compartments' of a spaceship as there will be forces that would affect the whole of the ship, as mentioned already (even wear/tear on interface surfaces). Likely better to just spin the whole thing, which brings other factors into consideration, etc, etc... Space travel has a long ways to go research-wise before we see anything practically applied.

Alex

[Ara Pacis]

It's not clear. Certainly you're not going to see a rotating "compartment" any time soon. The required radius of rotation may be on the order of hundreds of meters, so the only thing plausible in the near term is a crew module on the end of a long tether/pole.

Yes, for Earth equivalent gravity at a slow enough spin to avoid causing anybody problems from spin. Some say that 3 RPM is appropriate and some say slower is better. At 3 RPM you get 1g at 100m radius. But why would you need Earth equivalent gravity? You might be better off using a Mars equivalent, which would decrease the radius to about 35m at 3 RPM.

I bet that there won't be (large) 'rotating compartments' of a spaceship as there will be forces that would affect the whole of the ship, as mentioned already (even wear/tear on interface surfaces). Likely better to just spin the whole thing, which brings other factors into consideration, etc, etc... Space travel has a long ways to go research-wise before we see anything practically applied.

Or if the rotating section is small enough, you might simply enclose it in a non-spinning, air-tight envelope. Think of a salad spinner.

[Noclevername]

Or if the rotating section is small enough, you might simply enclose it in a non-spinning, air-tight envelope. Think of a salad spinner.

You'd probably feel like you'd been in a salad spinner too. But a separate set of compartments linked by elevators would be easier to build using existing spaceflight technology.

As for rate/size of the spinner, I just want to point out that all the centrifuge tests so far have been conducted either in a 1-G field, which would slew the inner ear all over and skew the results, or in an extremely confined space, so we don't actually know how big a real weightless rotator where the only source of balance is the spin itself will have to be to avoid vertigo, if there even is any.

[Siguy]

For a habitable centrifuge to be practical, I would think it would have to be at least the volume of the current ISS. If one were to be installed, life support systems on the ISS would have to be doubled.

[aerovoid]

Here's a site some of you might find useful. Spin Calculator

[Philippe Lemay]

I think we'll have a good, solid theoretical explanation for quantum gravity within a thousand years. That will either give us a real possible method or rule it out entirely.

Rule it out entirely I'd imagine. The gravity force is unimaginably weak, so that even if we could figure out a way to pump EM energy into a machine to produce gravity, you would need such ridiculously large amounts of power to run the damn thing, you might as well use the continuous acceleration method, and get to your destination more quickly.

[Philippe Lemay]

However It would be a good way to store energy too. A solar powered motor/flywheel/re-generator energy storage and recovery unit.

I like this idea. Have 2 rotating modules for stability, and in the center you have yourself a giant flywheel battery to store extra power and help keep the station centered.

[Philippe Lemay]

I wouldn't be too sure about that. That would be a lot of extra expense for hardly any return in knowledge.

If they don't build a prototype on the station first, then they will at least keep the spacecraft in Earth orbit for a while to see if she runs alright. As it's been said, the rotating tether/compartment thing will have a lot of potential engineering problems. It won't be easy to fix something on the way to Mars if it breaks. So I'm thinking they will want to at least try out a relatively stationary model before they send it out zipping across millions of miles of space.

[AlexInOklahoma]

Before worrying about gravity, the main issue is radiation killing a person Engineer *that* first, then worry about gravity generation. No need to worry about bone weakness or whatever on dead people, right?

Once the needs are met for radiation shielding, then you will know how much mass/fuel/money will be available for use to try for Mars, etc... First things first - gotta live outside of the VanAllen areas......

Have any ill-effects been shown from low-gravity conditions? Aware of any long-term issues? Or is exercise/resistance good enough for relatively short missions (Mars is not all that far away)? Is no gravity a *serious* issue that is not reversible easily? What is trying to be fixed by creating gravity? And how much would be needed should something be found detrimental? (hint: gotta study it first *then* engineer to a known problem, not the other way around as the design may make a problem worse)

ISS will *never* have anything rotating around it. Not ever. It cannot withstand forces as such and does not have mounting points, etc, etc. It will splash within the next decade or so and takes longer than that just to design/build/launch something designed specifically for it originally And there will probably not be a larger (or other) 'space station' anytime soon with so many other problems/missions to be overcome/accomplished first. The generation of 'gravity' is low on list of must-do's right now, I think. The study of the effects should be higher on the list, but that is another matter of debate.

Alex

[Middenrat]

Eh.. more practical than a spinning compartment? Honestly I don't know of any other way to simulate gravity in a real-life setting. Aside for accelerating continuously at a pretty high rate, but that seems even harder.

I'm very curious, what would this other solution involve?

How about using electromagnetic force? The floorboard being one pole, the other a bodysuit. You could walk on a grid of insulating material all the while experiencing a downward force distributed evenly through careful tailoring.
So shoot me down in flames, it can't be this simple.

[Ara Pacis]

Rule it out entirely I'd imagine. The gravity force is unimaginably weak, so that even if we could figure out a way to pump EM energy into a machine to produce gravity, you would need such ridiculously large amounts of power to run the damn thing, you might as well use the continuous acceleration method, and get to your destination more quickly.

Probably, but there might be some intriguing possibilities once we know how it works. Instead of creating gravity from scratch, we might discover that we can magnify gravity in a certain direction and use it as a propulsion source or as a method to provide gravity in a ship orbiting a large planet or a large ship/station that has a large mass at its center. Or maybe we can block gravity, which might allow for large masses to be more easily moved. Or maybe we might produce antigravity for use as a propulsion method. I don't think these ideas are likely, but we won't know how it doesn't work until we know how it does work.

[Vultur]

I don't know where you heard that, but it's really the only option for long-term human survival in space.

Not sure about that. It may be the only option for very-long-term (multi-year; people have come back after 1 year on the ISS, so anything <1 year is provably doable without it) missions where a return to Earth is planned (permanent Mars colonists have no need for it, since they'll never have to deal with more than 1/3 g).

Actually, Mars missions wouldn't need it anyway, that's c. 8 months in microgravity each way, which has been done before - and on Mars, heavy exercise in 1/3 g ought to be enough. (Perhaps, if the spacesuit isn't heavy enough on its own, just have a weightpack that simulates the distribution of weight on the human body in 1g.)

And I don't see why the ISS-method isn't extendable indefinitely anyway... sure, you'd be weak on return home, but that would recover, wouldn't it, just as exercise always builds muscles???

[samkent]

In the recently canceled series Defying Gravity they used magnetic suits and floors. With today’s tech you might not get 1g but it would have to help with the atrophy problem.

[mugaliens]

How about using electromagnetic force? The floorboard being one pole, the other a bodysuit. You could walk on a grid of insulating material all the while experiencing a downward force distributed evenly through careful tailoring.
So shoot me down in flames, it can't be this simple.

It isn't, and electromagetics do not require an insulator.

Actually, electrostatics would work better, and it's been done (they actually suspended a positively-charged guy mid-air here on Earth above a positively charged plate and below a negatively-charged plate). But the electric fields play havoc with all electronics (as to magnetic fields) and consume a lot of energy, so it's impractical.

[Sharlos]

Not sure about that. It may be the only option for very-long-term (multi-year; people have come back after 1 year on the ISS, so anything <1 year is provably doable without it) missions where a return to Earth is planned (permanent Mars colonists have no need for it, since they'll never have to deal with more than 1/3 g).

Actually, Mars missions wouldn't need it anyway, that's c. 8 months in microgravity each way, which has been done before - and on Mars, heavy exercise in 1/3 g ought to be enough. (Perhaps, if the spacesuit isn't heavy enough on its own, just have a weightpack that simulates the distribution of weight on the human body in 1g.)

And I don't see why the ISS-method isn't extendable indefinitely anyway... sure, you'd be weak on return home, but that would recover, wouldn't it, just as exercise always builds muscles???

I don't know about you but when discussing space travel I don't consider 1 year anywhere near long term.

[Tuckerfan]

I don't have the link any more (if someone can dig it up, I'd be ever so grateful, since my google-fu is weak today), but NASA recently announced that putting an astronaut in a centrifuge for only about an hour a day is enough to ward off muscle atrophy. I can't remember if it required only a partial G or multiple Gs to achieve this, but it wasn't a heck of a lot to ask someone endure, I remember that.

If you're going to go to Mars, this is probably the really big issue (I know, I know, radiation, I'll get to that in a minute) to deal with. According to an interview I heard with a space tourist, just being in orbit for a few days was enough to make being back on Earth a real endurance test. (There's also the issue of habits one acquires while in space. You can "park" a tool in the air when you're working on something, while in zero g, and it doesn't work quite as well on Earth, no matter how many times you try to do it [which returned astronauts do quite frequently, apparently].) Unless we send astronauts to Mars via a high speed rocket (continuous acceleration the whole way), they're going to be really weak when they land, which will delay the start of exploration as well as potentially put them in danger. (Because something went wrong, and they're too weak to try and fix the problem.)

Now, for the radiation part. If the sun "burps" out excessively while the crew is traveling (unshielded) to Mars, the levels of exposure can be lethal in a short period of time (days or weeks, as opposed to years or decades). The risk of this can be reduced by launching when the sun is at the low part of its solar cycle and is less likely to "burp" out lethal doses of radiation. Not a perfect solution, granted. Research into portable magnetic radiation "shields" which work similar to the Earth's magnetosphere has been extremely promising, and if properly funded could produce a solution in a few years. There's also been promising research into radiation vaccines (i.e. the vaccine would protect you from later exposure to high levels of radiation) and drugs which reduce or eliminate the damage caused by lethal levels of radiation exposure.

[Ara Pacis]

I don't have the link any more (if someone can dig it up, I'd be ever so grateful, since my google-fu is weak today), but NASA recently announced that putting an astronaut in a centrifuge for only about an hour a day is enough to ward off muscle atrophy. I can't remember if it required only a partial G or multiple Gs to achieve this, but it wasn't a heck of a lot to ask someone endure, I remember that.

I seem to recall hearing that too, but don't recall specifics or a link. It might help but it also takes a crewmember off of his job for that period of time. There's probably not much useful activity he can do while enduring that rapid spin, which has a short radius and significant coriolis forces.

Having portion of or all of the craft spin not only allows the crew to work the whole time but makes many mundane tasks much easier, like eating, sleeping and other bodily functions, and helps keep the craft clean.