I wrote a GDD for a concept very similar to this, with an astronaut who is trapped outside of his spaceship in an iron-rich asteroid belt. The ship is moving up and the asteroids are moving down, and the only control you have is the direction you run around asteroids and switching your magnetic boots on and off.
Once the magnetic boots are off, you drift with whatever momentum you were able to build up (linear velocity on a tangent from angular velocity at moment of release), until you reactive the boots and are pulled towards whichever rock is closest. You die if you go off the bottom of the screen or get squished between two asteroids, and you win if you get to your spaceship.
I had a few extra mechanics, like collecting minerals from the surface of the rocks, but the core concept was very similar to yours. Great minds think alike, eh?
One thing I would suggest, based on my own experiments, is that you don't necessarily need to model realistic gravitation between the various objects in the game. Sometimes realism goes too far, to the point that it isn't actually fun. Sometimes, it is more fun to have something that only vaguely approximates the laws of physics. Weigh the benefits of realistic physics versus the extra complexity, runtime overheads, player expectations, etc., you might find a better solution is far less complex but doesn't detract much from the actual gameplay.