A new type of aerospace engine to remove space debris

Abstract

We present a design concept for a space engine that can continuously remove orbital debris by using the debris powder as a propellant. Space debris represents a great potential threat to operational satellites, especially certain high-value spaceships. With the increasing risk of debris, researches reveal that it would reach a phenomenon named the Kessler syndrome that numerous operational satellites being destroyed in a chain reaction in low orbit in the not-far distant future. Initiative removing enough of the debris for the safety of space flight is an inevitable problem for human. Major space organizations are monitoring debris constantly with space debris environment models. At the same time, researchers have proposed a series of methods for removing the debris, such as using electrically conductive tethers to deorbit the debris, using robots with claws, nets or gecko-like suction cups to capture the debris and deploying ground-based or space-based laser to deorbit the debris. Nevertheless, large consumption of fuel for orbital transfer especially noncoplanar, chasing and rendezvousing with the debris is the leading restricting factor. In the concept of debris engine, a robotic space cleaner is used to capture the targeted debris and transfer it to engine. Large debris is firstly disintegrated into small pieces with diameters smaller than one centimeter using a mechanical method. A planetary ball mill is used to grind the pieces into powder with diameters of one micrometer or less. The energy required for this process is obtained from solar power or nuclear. The debris powder is then charged by electron beam. This charged condition can be used to accelerate the movement of the powder in a tandem electrostatic particle accelerator. Continuous thrust is generated by ejecting charged powder from the nozzle of engine because of momentum transfer. This thrust allow the spacecraft and robotic cleaner to perform orbital maneuvers and to rendezvous with other debris. The ejected charged particles will be blown away from the circumterrestrial orbit by solar wind and the effect of Earth magnetic field. Thus, digesting the space debris not only removes the orbital debris but also provides the necessary thrust to propel cleaner. Numerical simulation reveals the specific impulse of debris engine is determined by the accelerating electrostatic potential, charging potential and the charge-to-mass ratio of powder. In addition, the thrust of engine is largely dependent on the mass flow rate of the charged powder at the nozzle and nozzle jet velocity of the powder. With optimal regulation of the specific impulse and thrust, spacecraft can follow an optimal trajectory. In addition, this approach provides a new concept for asteroid exploration and interplanetary flight using a sustainable fuel supplement.