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Why no Artificial Gravity ??

Just thinking

Philosopher
Just thinking
Joined
Jul 18, 2004
Messages
5,169
Basically, why are there no plans to create near future spacecraft with some sort of artificial gravity? No -- not the Star Trek / Hollywood type, but the simple rotational 2001: A Space Odyssey type.
 
Just thinking said:
Basically, why are there no plans to create near future spacecraft with some sort of artificial gravity? No -- not the Star Trek / Hollywood type, but the simple rotational 2001: A Space Odyssey type.
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I have no idea. It seems perfectly reasonable to me. I'm guessing the main problems are logistics. To get a rotating ring with a radius which is large enough so that standing up does not create weird rotational differences between your feet and your head into space would cost a lot of money.
 
Taffer said:
I have no idea. It seems perfectly reasonable to me. I'm guessing the main problems are logistics. To get a rotating ring with a radius which is large enough so that standing up does not create weird rotational differences between your feet and your head into space would cost a lot of money.
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It doesn't have to be that elaborate -- two identical bodies joined by a long enough shaft would do the trick. And one doesn't have to go for a full 1-G ... in 2001 (the novel) the huge space station only had 1/3 G.
 
Just thinking said:
Basically, why are there no plans to create near future spacecraft with some sort of artificial gravity? No -- not the Star Trek / Hollywood type, but the simple rotational 2001: A Space Odyssey type.
Click to expand...

Because to get much gravity you are talking a truly huge structure. And then you get all kinds of strange rotational effects like strong Coriolis effects when you walk.
 
Just thinking said:
It doesn't have to be that elaborate -- two identical bodies joined by a long enough shaft would do the trick. And one doesn't have to go for a full 1-G ... in 2001 (the novel) the huge space station only had 1/3 G.
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So you want your spaceship to be several miles long? And spinning like that?

It is not practical when every ounce counts to spend that much weight on something like that.
 
I was thinking of this last week. If we are truly planning to go to Mars, wouldn't we need some sort of artificial gravity? Otherwise, there would be too much trouble with de-calcification of the bones and wasting away of muscle.

That doesn't even get into the sex thing, but that's a whole other thread! ;)
 
This is truly a good questions. There are a number of reasons that creating a gravity effect with centripetal force is currently impractical. There are many tradeoffs to spacecraft design. The largest restrictions are weight and cost. Everything that gets into space has to come from our planet and it's very expensive to lift each pound of material. (most of the weight on the ground before liftoff is fuel, more mass means more engines and more fuel, more structure, etc.) Due to those restrictions, spacecraft are very small. A small craft would need to be spun very fast to create any significant force and that would make crew very dizzy, disoriented, and somebody already mentioned the coriolis effect. There would also be a huge gravity gradient, strong at the "floor" weak at the head.

Another issue is energy. The spacecraft would need to be rotated by applying an angular force either using thrusters or reaction wheels. Thrusters burn fuel which is very limited on spacecraft. Reaction wheels can use electrical energy (Sun) but may not work too well with flexible spacecraft (like 2 tethered pods).

Space navigation requires occasional burns to correct the path. The spacecraft would likely have to be "despun" for each correction.

While this concept is actually theoretically possible and may be used in the far future it is currently impractical in reality.

We are just infants in our manned space program. We have a lot of evolving to do.
 
I just wanted to add that current methods for reducing muscle and bone loss include using bungee cords to hold crew onto a treadmill and other resistance based exercises. (amazing how rapidly the human body adjusts itself to varying environments!)
 
I can't envision long term space craft like the Odyssee or the Alexi Leonov, both of which rotate a section while keeping the rest of the craft motionless, could work. You're going to lose some energy due to friction no matter how well designed you are, and that means fuel lost to keep it rotating and keeping the rest of the ship from starting to rotate in the other direction.
 
"Zero-G"* is a good thing, in spacecraft: There is more freedom of movement within a confined space. Most astronauts will tell you that the insides of a ship feel larger, when it is in space, than when it is not.
And, you don't need ladders to reach high shelves.

*And, yes, I am aware that it is not really zero-G. There is still gravity in space. I simply used the words "Zero-G" because it is the common phrase people use in such situations, and hence the quotes around it.
 
It's really not that cost effective to send people into space. Our robots don't require such a delicate environment. They use much less power and can do more things. I think we should still send people into space and grow that technology, but I am against sending a person to Mars unless there is a good reason. We will make our own future. The reason we don't send people to the moon anymore is that there is no need. There may be a need one day, but now there is not.

The ISS is a cautious step in the right direction. I think the next step will probably be a moon base, with it's natural gravity. A spinning space structure with artificial gravity may be the next step after that, but where will such a station be needed? Orbitting Mars? That step is a doozy.
 
Don't some plans for a Mars spacecraft call for a habitation module connected by a long cable to the expended final stage of its launch vehicle (as a counterweight) and set spinning to simulate gravity?
 
RenaissanceBiker said:
I think we should still send people into space and grow that technology, but I am against sending a person to Mars unless there is a good reason...I think the next step will probably be a moon base, with it's natural gravity.
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Maybe I'm misremembering, but I was under the impression that sending stuff one-way to Mars (i.e. to establish a base) was actually cheaper than going to the moon, at least in terms of fuel economy, because you can decelerate with aerobraking and have parachute-assisted landings.
 
My first instinct tells me that unless the cable/umbilical that tethers the two opposing, equal mass capsules in rotation was at least a mile long, there would likely be some inner ear/vertigo thing going on when you tilted your head. The longer the tether the lesser the effect. But I have noticed that in flight training, being in a small, sealed capsule w/no windows, even a slow rotation caused this vertigo effect in me when tilting my head even slightly out of axis.
 
Brian Jackson said:
My first instinct tells me that unless the cable/umbilical that tethers the two opposing, equal mass capsules in rotation was at least a mile long, there would likely be some inner ear/vertigo thing going on when you tilted your head.
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Yeah, I'm sure that would be an issue, but it looks like something they've taken into consideration. From what I can tell, the Mars Direct plan would call for a 1500-meter cable, providing 0.4g for the outbound trip (unfortunately, the counterweight would be jettisoned on arrival and there would be no gravity on the way home).
 
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