I have two circles, the smaller circle of which revolves around the other bigger circle (simulating an orbit). When the user clicks with the mouse, there is an impulse applied to the small circle which jumps. I want that if the smaller circle lands back on the bigger circle, it goes back into orbit again and its speed and direction ( clockwise/anticlockwise) change depending on the point of impact. I am using the physics behavior but there are a lot of irregularities. Can someone suggest a way to do this? Many thanks.