Bringing Massive Derelicts Back to Life

D. McKnight et al. (2019), JBIS, 72, pp.410-415

Refcode: 2019.72.410

Abstract:
The growth of the future debris population will be largely driven by collisions between massive derelict objects (i.e., abandoned rocket bodies and defunct payloads). The traditional approach to reducing the possibility of such an event is active debris removal (ADR) whereby a large object is grappled, detumbled, and moved into a re-entry trajectory. Due to the enormity of these objects (i.e., 1,000 to 9,000 kg) the ADR operations will be taxing and the re-entry hazard will be significant. As a matter of fact, it is likely that all of the objects with mass greater than 1,000 kg will require controlled re- entry which will add even more stringent requirements to the ADR solution. This paper proposes an alternative to prevent massive objects from colliding. It is proposed that one or more small (i.e., 3U to 6U CubeSat) satellites, called nano-tugs, be attached to massive derelicts. A nano-tug would have (1) a simple grappling mechanism, (2) an electric propulsion system, (3) embedded accelerometers, and (4) a Global Positioning System (GPS) transceiver. This combination would, in essence, provide the massive derelict object a rudimentary collision avoidance capability coupled with enhanced position determination capability. In essence, the derelict objects will have been transformed from debris into a part of the space traffic whose safety will be managed through the expanding Space Traffic Management (STM) constructs. Mathematical models of the requirements of a nano-tug are reviewed and potential engineering solutions for these requirements are discussed. Key engineering parameters are identified and characterized: attachment mechanism, maximum possible encounter velocity, power source, number of nano-tugs needed, and scale of electric thruster systems.