captured rotation and geosynchronos orbit

[Beeblebrox ate my hamster]

For example I have created a model of a gas siphoning space station to orbit a gas giant at a low altitude (marvellous view with a ringed planet!) but I want it to keep the business end of the thing pointed at the planet at all times.

Also how do you find the geosynchronos orbit for any object, am I missing something remarkably simple (too many Pan Galactic gargle blasters at Xmas time!)

[granthutchison]

For example I have created a model of a gas siphoning space station to orbit a gas giant at a low altitude (marvellous view with a ringed planet!) but I want it to keep the business end of the thing pointed at the planet at all times.

If you don't specify a RotationPeriod in the ssc, Celestia will automatically maintain synchronous rotation for you. You may need to tweak the orientation of your model, however, using RotationOffset or the Orientation command, so that it's initialized with its business end pointing at the planet.

Also how do you find the geosynchronos orbit for any object, am I missing something remarkably simple (too many Pan Galactic gargle blasters at Xmas time!)

Simple solution is to forget the physics and just set the Period of your space station's orbit equal to the RotationPeriod of the gas giant.

Complicated solution is to get the physics right, and calculate the correct SemiMajorAxis to go with the Period you've worked out above:

a^3 = G*M*P^2/(4*pi^2)

where M is the mass of your planet, P is its rotation period, a is the semimajor axis of the space station's orbit and G is the gravitational constant.

Grant

[Beeblebrox ate my hamster]

thanks for all that , I think I'll avoid all the maths though !