New Insights Into Additive Manufacturing Processes: Enabling Low-Cost, High-Impulse Propulsion Systems

Recent propulsion system trade studies conducted have concluded that traditional chemical propulsion systems, when scaled down to CubeSat sizes, deliver vanishingly small amounts of impulse per unit volume, even when the smallest available COTS components are assumed. This effectively has created a barrier that seemingly can only be broken with the employment of cold gas systems, due to their reduction and simplification of propulsion system components and the relative ease of the system design itself. Further disadvantages of chemical propulsion systems have included toxicity-related handling restrictions, barring most mission planners from considering these types of systems for secondary payload propulsion trade studies. Use of low-toxicity alternatives has been hindered by a disparity between the typically very limited power budget of nanosatellites and the associated high preheat temperatures required with current state-of-the-art green ionic liquid monopropellant thrusters. Aerojet has developed a comprehensive solution by demonstrating that additive manufacturing processes, combined with miniaturization of propulsion system components, can be employed to break through this barrier by multi-purposing the system structure to replace traditional add-on components, maximizing the use of dry volume, and minimizing the number of overall components and required assembly steps. This results in a propulsion system that can be packaged into a 1U volume that can bolt onto, or be integrated within, a standard CubeSat chassis, for costs low enough to support the simplest of missions. This system can be tailored for multiple levels of ΔV capability, depending on the mission planner’s requirements, by employing a variety of propellants ranging from cold-gas condensable, hydrazine monopropellant, or AF-M315E green advanced monopropellant. This results in ample ΔV capability to enable CubeSat missions like orbital debris management, constellation deployment, scattering and coalescence, or simple drag-makeup to support newly-emerging low altitude imaging applications. This system has been designed from the start with input from range safety personnel to ensure compliance to AFSCM91-710.