Abstract: A cloud of small to medium-sized space debris is mitigated by releasing drag-reducing particles into the cloud from a dispenser vehicle, causing the particles to collide or otherwise interact with, and thereby exchange momentum with, the debris particles, reducing the orbiting velocity of the debris to a degree sufficient to cause the debris to de-orbit, or to accelerate the de-orbiting of the debris, to Earth. Certain embodiments also include a shepherd vehicle containing systems for identifying and tracking the debris cloud and for coalescing the debris cloud to increase the particles density in the cloud.

Abstract: A thrust vector control system for a plug nozzle rocket engine for propelling and maneuvering a vehicle is disclosed. The plug nozzle rocket engine includes a housing having a nozzle throat, a plug disposed within the housing and positioned within the nozzle throat to define a space between the plug and the nozzle throat, and a thrust diverter moveably disposed relative to the housing to define an asymmetric pressure distribution along the plug for thrust-vectoring. In one embodiment, the thrust diverter is normally biased to a non-thrust-vectoring position, but is moveable in a plane substantially perpendicular to an axis extending longitudinally through the plug.