On Sun, Jan 21, 2018 at 04:35:03AM -0500, Caleuche wrote: > In fact, around asteroids and planetoids, the space station operator > would have to be careful as an object in a powered orbit like that > is effectively a gravitational tractor, and will change the orbit of > the planetoid around its primary star over a long enough period of > time. Even a very slow rotation would mean that the average long-term gravitational force of a synchronous object would go to zero. If contragrav is employed, the gravitational attraction would be essentially zero anyway. Barring both, the worst case would probably be something like a million-tonne station maintaining a solar synchronous position at some very close range like 10 km, causing an acceleration on the order of a few millimetres per second per year. It might become a problem if the station is still in the same orbit-relative direction throughout a million years. Gravity is an extremely weak force on human scales. - Tim