1. Jul 12, 2014

FlyingKiwi

Hey all,

I recently read a bit about proposals to induce "artificial gravity" on a mars mission by spinning two sections of a spacecraft on a long cable in order to create a centrifugal force that would simulate gravity by pulling astronauts outward toward the floor of their capsule, or, similarly, a space station that consisted of a very large ring spinning at a certain RPM. My initial thought is that as people moved around within the spacecraft or station, it could shift the center of mass, thereby causing some weird effects that would have to be somehow compensated for, though perhaps I'm mistaken in assuming this.

My question is whether or not the rotation of the said objects would be maintained, or if additional propellant would be required to periodically "re-boost" the rotation of a station or spacecraft in order to maintain the desired RPM?

Thanks!,

-FK

2. Jul 12, 2014

UltrafastPED

The usual proposal is to have two (or more) balancing arms, or even a ring, that is revolving.

Since there is no air resistance in space, there should be little need to boost the rotational speed, but there will be attitude adjustments due to the solar wind.

3. Jul 12, 2014

FlyingKiwi

Interesting, thanks. Two more questions:

- Could the rotation of the station/spacecraft be initiated by a reaction wheel or control-moment gyro like many satellites use? If not, why?

- Any idea why this hasn't been attempted in space? It doesn't seem like one would need to add a significant amount of mass to the orbital payload in order to get, say, a 100-meter cable into orbit that could attach a spent booster to a spacecraft. Assuming the center of mass was exactly between the two objects, if I've calculated this right, you'd only need an RPM of 4.2 to induce a centrifugal force equivalent to that of earth's gravity at the surface (if R = 50m, V = 22 m/s)

Thanks!

-FK

4. Jul 13, 2014