Benchmark Space Systems proposes a resistojet micropropulsion system that leverages a solid gas generator to offer high-performance, low-cost propulsion with key safety features. This system is designed to offer 1600 N•s in a 2U frame.
The design calls for one central thruster that will provide 0.2 N of thrust. The resistojet thruster uses a patent-pending exothermic Warm Gas Generator (WGG) that decomposes from a single heating point once on-orbit. The gas is held at high pressure and released through a regulator and valve to supply consistent and controlled flow to the nozzle. Inside the nozzle chamber, the gas is heated to high temperatures (up to 1000° C) to increase efficiency. At these elevated temperatures the system can achieve an estimated specific impulse up to 175 s.
The fuel for this warm-gas resistojet system is Azodicarbonamide (ADA). ADA comes in a powdered form and is Department of Transportation approved for shipping. It is most commonly used in plastics manufacturing and commercial baking. It is safe to handle and non-toxic.
ADA undergoes an exothermic decomposition reaction when raised to a critical temperature. A rapid decomposition occurs at temperatures above 230° C. The resulting gas is a blend of N2, CO, CO2, and NH3. Once started, the reaction takes <1 second to propagate through the entirety of fuel in the tank. The warm gas produced has a specific impulse of 86 s with no additional heating. Increasing the temperature in a resistojet system will provide a specific impulse of 150-175 s depending on power input. Benchmark is targeting 15 W and 150 s for the initial design.
This SBIR Project by Benchmark Space Systems will develop an efficient and benign chemical propulsion system for small satellites. The goal of the project will be to design and integrate the propulsion system into a CubeSat mission. Phase I will produce a benchtop model to characterize the system and design a prototype model to be built during Phase II.
This technology benefits many future NASA missions. Earth orbiters like CIRAS and IRIS can use the proposed system to reach target orbit when launched as a secondary payload, opening a wider range of launches that are lower cost or launch earlier. They can also use this system for lifetime extension, increasing chances for mission success and lowering average lifetime cost. Missions beyond Earth’s orbit - like Lunar Flashlight or INSPIRE- can use this technology for orbital maneuvers when escaping or approaching a target orbit.
Private and defense satellites also benefit from the proposed technology. Commercial can operate at lower costs by using Benchmark Space technology for lifetime extension. Defense missions can reduce risk by transitioning operations from large satellites to constellations. Benchmark’s proposed technology provides the precision and agility necessary for these types of risk-mitigating formations.