- #1

James Demers

- 59

- 32

Deimos and Phobos have every appearance of being captured objects - but one can imagine collisions providing the needed orbital injection forces. Other examples, if they exist, are pretty rare, given the billions of years of opportunity.

Newtonian trajectories are conic curves (hyperbolic, parabolic or elliptical), and transitioning from one to the other would seem to call for the application of force. My main question is, can an inert object be captured from a hyperbolic/parabolic trajectory into a stable orbit, or is acceleration required? (Would an observer locked within the object be able detect the event with an accelerometer?)

Relatedly - more as a question of orbital mechanics than of physics - as object A approaches planet B on a hyperbolic/parabolic trajectory, could the gravity of a third body C put object A into orbit around B? For an object approaching, say, the Earth-Moon system, stable orbits are hard to come by, but given three bodies and no initial orbits, can an orbit be produced?