Electrospray-Based Propulsive De-Orbit Module

ABSTRACT: Busek proposes to developed a self-contained electrospray thruster that (a) requires no pressurized propellant tanks or valves, utilizes analog-only electronics, and stores propellant as a stable solid; (b) is capable of operation after extended storage and inoperative periods of up to 15 years; (c) exercises full control authority over a spacecraft with capability to apply torque to the spacecraft in a de-tumbling mode and is capable of thrusts sufficient for de-orbiting; and (d) has minimal mass, volume, and power requirements, promoting ease-of-integration with spacecraft. The concept that Busek proposes consists of an electrospray utilizing a high melting point ionic liquid propellant, capable of stable extended storage with no leakage and requiring no valves. Thruster operation is initiated via a low-power heater that melts the propellant. Propellant distribution is accomplished via passive wicking, eliminating the need for valves and pressurized feedsystem. Thruster control shall consist of sun sensors and analog logic with simple instructions to perform retrograde firing into the sun following emergence from eclipse, while maintaining correct spacecraft orientation. This constitutes half of a Hohmann transfer maneuver, gradually lowering perigee of orbit to altitudes of increasing atmospheric drag and eventual de-orbit. BENEFIT: The risk of spacecraft collisions grows significantly with the number of items in orbit and is a particular problem for heavily used orbits, where debris density is highest and collisions cause further debris break-up. It is anticipated that future regulations on space debris management will eventually require all spacecraft to perform de-orbiting maneuvers at the end of life. The proposed propulsive module utilizes a high-efficiency, low power, electric propulsion module that will provide a stand alone, independent system capable of de-orbiting a variety of commercial and military spacecraft, without significantly impacting overall spacecraft design.