Description: The two primary methods of deorbiting a spacecraft involve either applying drag or using a propulsion system. Atmospheric drag, tethers, and solar sails are examples of the former, and chemical propulsion and electric propulsion are examples of the latter. The orbit height, spacecraft mass, and spacecraft "frontal area" will determine the velocity change requirements and the time frame over which a system can deorbit a spacecraft. The minimum-mass solution for a given time frame will generally involve the use of both drag and propulsion: use a propulsion system to lower the spacecraft orbit and then let atmospheric drag further slow the spacecraft to complete the deorbit maneuver. In this project, Ultramet will investigate the propulsion and drag requirements for a minimum-mass system, and then focus on the development of a suitable propulsion system. Specifically, Ultramet will mature its existing green propulsion technology, and its high-reliability low temperature ignition system that is being developed for the Air Force, and apply them to the development of a high specific impulse (>300 sec) hybrid rocket with low size, weight, power, and cost (SWaP C) that can be used to lower the orbit of a small spacecraft to the point where atmospheric drag can complete the deorbiting process within the desired time frame.

Benefits: The propulsion system to be developed can be used not only to deorbit small spacecraft, but also to perform high-impulse orbital maneuvers. This includes orbital insertion burns, moving spacecraft up to geostationary orbit, plane change maneuvers, and phase change maneuvers. Because the technology will have the simplicity of a monopropellant system, but much higher specific impulse, it can potentially be used in any application where high-reliability monopropellant systems are used.With the proliferation of small commercial spacecraft in low Earth orbit and more constellations planned, the number of spacecraft owners needing deorbit capability is growing exponentially. As with government spacecraft, the technology can also be used for performing high-impulse orbital maneuvers such as orbital insertion, geostationary climb, plane change, and phase change.