canopus56 wrote:
snip

This page may also help the thread top-poster:
http://www-astronomy.mps.ohio-state....t4/orbits.html

These lecture notes by an Ohio State professor note that to sustain a
exactly circular orbit, velocity of the smaller body must be, per
Newtonian gravity:

v_circular = Sqrt( ( G*M ) / r )

where r = radius, G is the gravitational constant, and m is the mass of
the larger first body.

If the initial velocity of the smaller body when captured is slightly
more than v_circular, the orbit will change into an ellipse. The
ellipse will grow larger until escape velocity is reached.


- Canopus56