Low cost orbit transfer of inoperative satellites by a service vehicle

Tumble Orbit Transfer, which is an effective method of re-orbiting inoperative satellites is described. This is done by an independent service vehicle equipped with a long arm and a grapple mechanism on top of it. After grappling the target satellite, the service vehicle orients its axis perpendicular to the orbit velocity vector. Then a thruster is activated to give an impulse on the service vehicle, which simultaneously causes velocity change and tumbling of the combined system. Since the angular momentums of two masses are exchanged periodically, separation at a selected instance will bring each mass into different orbits, one with a higher energy and the other with a lower. Separation soon after the impulse application puts the target satellite into an elliptical orbit, and separation after a half orbital period puts it into a higher circular orbit, assuming the original orbit is circular. The amount of total impulse is exactly half of that required in a conventional method. In case the service vehicle returns to the original orbit after injecting the target into the new orbit. The required total impulse is further reduced to one-third maximum. Another important feature of this method is the ease of capturing. Because the dominant force during and after the impulse application is tension through the arm, bending rigidity in the capture mechanism is not required. Therefore, a simple grapple will be enough for this maneuver. Small fuel requirements and simple capturing make this method attractive for transferring orbiting objects, and only this will provide a method of re-orbiting inoperative satellites of arbitrary shape.