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Old 03-06-2013, 05:31 PM   #18
Agemegos
 
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Join Date: May 2005
Location: Oz
Default Re: GURPS Space - assistance

Quote:
Originally Posted by Anthony View Post
Uninteresting; you won't get star motion due to orbiting, but that's not human-visible to start with.

No, you want lagrange points.
Even Lagrange points have substantial gravity at them. They are characterised as the "points" in the synchronous rotating frame of reference at which the gravitation is exactly right to permit an object of negligible mass to participate in a circular orbit around the barycentre of the system that has a period equal to the period of the orbits of the principal components of the system.

The equipoise, the point at which the planet's and moon's (or whatever) gravity is equal and opposite is on the line between the planet and moon rather close to the moon, whereas the barycentre is closer to the planet. And the problem with the equipoise is that it doesn't stay still (as the barycentre does), nor does any possible trajectory at the point give you a circular orbit with co-incident period. "Park" your ship at the equipoise and what happens is that the equipoise moves away following the moon in its orbit. And no possible velocity that you give your hip at the equipoise will make it keep up with the equipoise as it moves.
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Last edited by Agemegos; 03-07-2013 at 06:02 PM.
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