High-Performance Deorbit Engine with Minimal Power Requirements, Phase II

Deorbiting a satellite generally involves either applying drag or using a propulsion system. The orbit height and the satellite mass and “frontal area” will determine the velocity change requirement and the time frame over which a satellite will deorbit. The minimum-mass solution for a satellite in a higher orbit will involve the use of both drag and propulsion: a propulsion system to lower the orbit and then atmospheric drag to further slow the spacecraft and complete the deorbit. In this project, Ultramet is focusing on the propulsion system. Specifically, Ultramet is leveraging its existing green propulsion technology and its high-reliability low temperature ignition system that is being developed for the Air Force, and applying 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 satellites to the point where atmospheric drag can complete the deorbiting process. In Phase I, numerous liquid oxidizers and hypergolic fuels were assessed, and a model was developed to calculate the propulsion system mass needed to lower the orbit of a satellite of arbitrary mass and frontal area from any orbital height so that atmospheric drag would complete the deorbit within the required five-year period. The most promising candidates were downselected, and bench-scale testing demonstrated hypergolic reactivity between the liquid oxidizer and the fuel grain where the downselected combination has a theoretical Isp of 320 sec. Hot-fire testing of a subscale engine was performed, which again demonstrated the reactivity between the liquid oxidizer and the fuel grain. In Phase II, the structure and composition of the hypergolic fuel grain will be optimized to maximize performance, and the system will be scaled up and hot-fire tested. Using data from the testing, a larger system will be designed to accommodate larger/heavier satellites and/or those in higher orbits.