Skeleton decay during long spaceflights

[JEL]

The human skeleton decays gradually when a person is not exposed to the stress of gravity, posing a potential health-problem for astronauts.

This happens to those on the ISS and those that might go to Mars or beyond.

So this is one problem that needs to be countered before long journeys will probably take place.

Only acceleration (IE gravity) can, atleast so far, counter this problem.

I've read that rotating spacecraft, like that in the movie "2001 a space odyssey", is not really viable.
The bigger ones because they're too hard to construct, and the smaller ones because the rotation would cause motion-sickness and related problems for those onboard.

But what about a half-way solution?
And this is just an idea I've thought of, and would like to hear some thoughts on. I don't know if it would work, but what do YOU think?
Here goes:

A "rotating sleeping-barrel gravitron 6000" (sorry, been watching too much lazytown recently )

A barrel or tube just big enough for 1 person to fit inside, which can rotate.

Think of this amusement-park ride to further grasp the idea:

Link: http://www.nasa.gov/missions/science/hyper.html

Or think of your washing-machine when it dry-tumbles and all the clothes get stuck on the edges due to the centrifugal forces.

Then the human body would be subjected to acceleration forces during sleep. This way the motion-sickness might be avoided, because you wouldn't be standing up and because you would be asleep, and the bone-decay atleast be slowed or maybe completely prevented because the body would experience atleast some gravitational-like stress.

What do you think? Could it work?

 

[Ghostrider]

If you don't want your skeleton to decay, do as I do and put it in a closet.

 

[Linguofreak]

Even if you were lying down, it would still make you very, very, very dizzy. You would not want to sleep in such a contraption.

 

[Andy44]

I think small centirfuges are okay as long as you don't spin them too fast. If light gravity is acceptable, then 2001's Discovery ought to work.

If you need more, you are just going to have to suck it up and build it bigger. It's not really that hard to construct; you're going to have to build a large structure no matter what, in order to cut down on reactor shield mass and to make room for all your equipment and lots of living space.

2001's Discovery was long because of the need for distance between the reactor and crew, and to make room for propellant and radiators along the spine; Clark could've designed it to tumble end-over-end instead of having an internal centrifuge. It's more stable like that, anyhow, that's why it settled into that spin mode by the beginning of 2010 when the Leonov arrived.

About using a small centrifuge for sleeping, how would that not make you just as motion sick? Because you are lying horizontal?

 

[Suzy]

There was a similar thread at NASASpaceflight.com - one possible solution is to use a vibrating platform (mentioned in this article at Discover Magazine):

Biomedical engineer Clinton Rubin of the State University of New York at Stony Brook has discovered that high-frequency vibrations may also strengthen bones. Two years ago he reported that sheep held on a vibrating platform 20 minutes a day, five times a week for a year built up more new bone in their legs than a control flock. He hopes to launch a similar experiment testing humans in space in 2006. He says the treatment feels like "standing on a sidewalk when a heavy truck goes past. We are trying to trick the bones into thinking the muscles are active."

(The thread title gave me an image of a corpse in orbit :rofl

 

[Hielor]

There was a similar thread at NASASpaceflight.com - one possible solution is to use a vibrating platform (mentioned in this article at Discover Magazine):

Biomedical engineer Clinton Rubin of the State University of New York at Stony Brook has discovered that high-frequency vibrations may also strengthen bones. Two years ago he reported that sheep held on a vibrating platform 20 minutes a day, five times a week for a year built up more new bone in their legs than a control flock. He hopes to launch a similar experiment testing humans in space in 2006. He says the treatment feels like "standing on a sidewalk when a heavy truck goes past. We are trying to trick the bones into thinking the muscles are active."

(The thread title gave me an image of a corpse in orbit :rofl

Vibrators: The future of mankind in space.

 

[simonpro]

The problem with being spun whilst lying down is that it will not strengthen bones correctly. On Earth the major source of pressure is in the head-foot direction, and we need to replicate that in space to prevent bone degredation as effectively as possible.

 

[RisingFury]

You don't need to just sleep in the rotating chamber... you could place most of your living quarters in there...

 

[T.Neo]

2001's Discovery was long because of the need for distance between the reactor and crew, and to make room for propellant and radiators along the spine; Clark could've designed it to tumble end-over-end instead of having an internal centrifuge. It's more stable like that, anyhow, that's why it settled into that spin mode by the beginning of 2010 when the Leonov arrived.

Spinning end-over-end makes sense to me. Mass that would be otherwise useless in the cruise phase is now producing gravity, instead of having a completely different system taking up weight and space.

I think the Orion pulse propulsion spacecraft were designed to spin end-over-end to mimic gravity.

 

[eveningsky339]

Spinning end-over-end makes sense to me. Mass that would be otherwise useless in the cruise phase is now producing gravity, instead of having a completely different system taking up weight and space.

I think the Orion pulse propulsion spacecraft were designed to spin end-over-end to mimic gravity.

The Orion, apart from a few political issues regarding the use of nuclear bombs, seems to be our best shot at interplanetary space travel at this time. It's a pity NASA never followed through with it.

 

[JEL]

About using a small centrifuge for sleeping, how would that not make you just as motion sick? Because you are lying horizontal?

I was thinking more because you were lying still, as opposed to walking around.

The motion-sickness, as far as I understand, comes when the relative (to your body and head) acceleration-vector constantly changes direction (like when you are on a rolling ship or boat for instance)

When you walk inside a centrifuge you will feel these direction-changes very strong unless the centrifuge is very large.

But if you lie down, very still, that effect should be fairly small, or atleast less dominant and noticeable. I don't know if you could fall asleep, or stay asleep, while being centrifuged, but sleeping on a rolling boat on high seas is possible (and I think you're actually less prone to becoming sea-sick while sleeping, or maybe that's different from person to person)

one possible solution is to use a vibrating platform

Ahh, yeah I can imagine that would have an effect.
Micro-bursts of acceleration

The problem with being spun whilst lying down is that it will not strengthen bones correctly. On Earth the major source of pressure is in the head-foot direction, and we need to replicate that in space to prevent bone degredation as effectively as possible.

Good point.

 

[T.Neo]

The Orion, apart from a few political issues regarding the use of nuclear bombs, seems to be our best shot at interplanetary space travel at this time. It's a pity NASA never followed through with it.

Aside from a "few political issues", you also have potential for environmental damage and the probability of frying every sat in LEO.

And frying sats would be very, very bad...

 

[eveningsky339]

Aside from a "few political issues", you also have potential for environmental damage and the probability of frying every sat in LEO.

And frying sats would be very, very bad...

Environmental damage does not seem to concern NASA all that much, considering the use of some of their more toxic propellants (flourine and hydrazine come to mind).

I'm not familiar with the types of nuclear bombs that would be utilized, but as I understand it, the radiation would be limited to a small sphere of only a few kilometers, 20 at the most.

It's not a perfect idea, obviously, and the idea of shooting off nuclear bombs in LEO certainly isn't appeasing, but I still think it's worth a shot.

 

[T.Neo]

Using hydrazine and fluorine in rockets is nowhere near as damaging as creating radioactive fallout (Or spilling said propellants into the environment, for that matter).

Even if the environmental risk is acceptable, you'll still have people whining about it- remember that there has been a negative reception to even relatively safe RTGs being launched into space.

AFAIK even a single atomic device being detonated in LEO would fry many satellites, I dread to think what several would do. Sats are big business, and are an integral part of modern civilization, so I doubt anyone would be even slightly accepting of such a mission.

 

[simonpro]

Bear in mind that atomic bombs fired in low earth orbit would be rather dangerous for those on the ground, to the extent that I doubt they'll ever be used for propulsion apart from in very deep space.

 

[Andy44]

The electromagnetic pulse created by nuclear or thermonuclear explosives is what damages satellites and other electronic devices. On earth, the atmosphere carries away the energy of a nuclear blast, but in space there's no medium to carry the energy other than the bomb casing itself and, in the case of a pulse drive, the disk of propellant attached to one end of the bomb. The energy has to go somewhere, so it goes into EM waves such as light, microwaves, X-rays, gammas, and radio waves across the spectrum.

As simonpro pointed out, nuclear blasts in LEO also create eye burn hazards for hapless observers on the ground looking up at them.

The Orion drive, if it were ever used, would likely need to be boosted out of orbit by more conventional drives and not used until very far away. Even still, it would make for a nice, high delta-V mission.

 

[Nemoricus]

As far as nuclear EMP devices go, they need a thin atmosphere in an Earth strength magnetic field to actually do anything.

http://en.wikipedia.org/wiki/Electromagnetic_pulse

Just thought that I'd mention this.

 

[Andy44]

That's good info, thanks.

 

[Nemoricus]

Not a problem. I hope that it will help contribute to this discussion.

Carry on.

 

[simonpro]

As simonpro pointed out, nuclear blasts in LEO also create eye burn hazards for hapless observers on the ground looking up at them.

Actually I was mainly referring to the radiation produced. I vaguely remember from a course on the subject that each bomb fried by orion would, statistically, lead to an extra 7 cases of cancer. I believe they based that conclusion upon the increase in radioactive isotopes present in the atmosphere after high altitude tests.