fisher@dvinci.DEC (Burns Fisher, MRO3-1/E13, 231-4108) (04/18/84)
1) Several previous notes have talked about whether a person would be strong enough to stop Solar Max's rotation. Here is a point that no one seems to have mentioned: Assuming that Pinky gets himself beside the solar panel at 0 relative velocity, then hangs on an shuts off his MMU jets, his grip/arms/etc would have to supply a certain amount of centripital force to keep him from flying out at a tangent to the spinning spacecraft. The amount of force depends on the rotation rate, the radius of the spin, and the mass of Pinky/MMU. I don't know how much that amounts to, but since he was able to rendezvous with the panel, we have to assume that force is less than or equal to the force that his jets can give, which is only a few kg. (I think I heard around one pound per jet). Now suppose while he is hanging on, he cranks up his jets to produce force in the same direction (tangential). The jet's force simply adds to the centripital force, with the result being 2*(a few kg), certainly within range of even a weak person's muscles. Thus, I don't think that an astronaut's strength has anything to do with the problem. 2) >Why not just hold on and use attitude hold? >>It would come to some difficult-to-predict equilibrium, not stopped Sure it would if he had no propulsion, but he does! I contend that if he could hold on long enough, AND he had enough fuel, AND he could exert force on the solar panels in all directions to counter all the various precession movements the thing might make, that he could stop it. Undoubtedly, though, one of the various conditions above could not be met, and thus the wobble. Thank heaven for magnetic torqueing and clever ground controllers! Burns
russ@bmcg.UUCP (04/19/84)
My understanding, according to AvWeek articles, is that the MMU has only an attitude-hold mode, not an inertial position hold mode. The attitude-hold mode was critical for the dock-and-halt maneuver since the docking point was relatively near the man-sattelite center of gravity. At that position, nearly all motion is rotational, rather than translational. ...Russ Schnapp
warner@orca.UUCP (Ken Warner) (04/19/84)
[bugs] Could this be the space equivalent of steer riding in a rodeo? Grabing a rotating object in space could turn into a wild ride. Maybe this will be one of the asteroid miner's sports.