PDA

View Full Version : Practical creation of artificial gravity



Sticks
2006-Aug-30, 12:59 PM
In the various sci-fi films or programmes, such as 2001 or Babylon 5, there is the concept of creating artificial gravity by spinning part of the craft of space station.

How practical would this be and how much more expensive would the craft be. I was wondering if this would be an option for personned space flights to Mars.

jlhredshift
2006-Aug-30, 01:21 PM
The most practicle idea I've seen is the Tether method. Two sections of the craft are held together by a sufficiently long "wire" and then spun up to an appropriate velocity. Low tech and weight conservative are the ideas virtues. The need to "adjust" the spin parameters on a constant basis uses fuel and increases launch mass is the downside, but may be manageable.

antoniseb
2006-Aug-30, 01:32 PM
Some of the mission descriptions for the Mars trip I've seen include a long-ways spin-up of the vehicle after getting onto the main trajectory. My understanding was that they were trying to get about 0.1g for the cabin.

The only real difficulties are that the structure needs to be strong enough to keep things intact, and suddenly you have a floor, which may decrease the total usable space in the living area.

NEOWatcher
2006-Aug-30, 01:55 PM
In the various sci-fi films or programmes, such as 2001 or Babylon 5, there is the concept of creating artificial gravity by spinning part of the craft of space station.

How practical would this be and how much more expensive would the craft be. I was wondering if this would be an option for personned space flights to Mars.
Here's a relevant discussion. (http://www.bautforum.com/showthread.php?t=35364) I haven't re-read it to see how relevant it is to your question, but if I remember right, it should help.

If Bruce Willis spins it, then you get uniform gravity throughout the whole craft. :think:

Sticks
2006-Aug-30, 04:40 PM
Here's a relevant discussion. (http://www.bautforum.com/showthread.php?t=35364) I haven't re-read it to see how relevant it is to your question, but if I remember right, it should help.


Does this mean this thread needs to be locked and continue this discussion over there ?

There was a lot of scary math about rpm's which kind of lost me as I have not touched that kind of math for a good many years

I will meet you over there then

NEOWatcher
2006-Aug-30, 04:46 PM
Does this mean this thread needs to be locked and continue this discussion over there ?
Not necessarily...I just thought it might add to your thoughts.

neilzero
2006-Aug-30, 06:59 PM
All good answers. If we soon have CNT = carbon nano tubes with good specs, we can spin two space craft at about one rpm = revelutions per minute tethered about a mile apart. Present tethers do not provide sufficient safety factor. If the tether breaks suddenly, one of the craft COULD be thown into Earth's atmosphere where it would burn up.
One craft needs to have dimensons up to a mile to minimise correlis effects from the spinning. Current materials are marginal for a craft that large that is spining fast enough to produce almost 1 g. It is not clear that 1/10 g has any advantage to humans over no g. The CNT needs to cheap as well as good specs for a very large space craft. Neil

astromark
2006-Aug-30, 09:42 PM
If the space craft is in stable orbit like the ISS then as long as the angle of rotation was inserted as not to be intersected by the Earth. and the tether was of sufficient strength to give security. The only issue with this is that any supply or replacement craft wishing to dock with this now rotating mass would need to match that movement very carfully., Or just stop near enough to space walk across. None of that would be an issue for non orbital craft like a mission to mars. Obviously having 1g would make space travel much safer for all concerned. I do not see that 0.1g would be of any use at all. I would imagine 0.75 to 1.g is the target.

neilzero
2006-Aug-30, 10:06 PM
Hi astromark: The tethered pair will behave like a gyroscope. Unless I'm confused, the throw angle intersects, briefly, twice per orbit of the Earth for all planes of rotation.
As you said a collision is unlikely, if failure occurs enroute to Mars, but considerable course correction would be needed to get both craft to Mars, if the tether broke. Reconnecting the broken tether would require even more delta v. Neil