CU Aerospace (CUA) proposes the further development of an alternative very low-toxicity Monopropellant Propulsion Unit for Cubesats (MPUC) and delivery of a brassboard MPUC system (TRL 5) which comprises a 150 mN main thruster subsystem (tested to TRL 6) and its TRL 5 feed system at the end of Phase II. CMP-X (CUA Mono-Propellant 10) is a non-detonable yet energetic COTS formulation that possesses many system-level advantages including lower cost (COTS propellant and non-refractory thruster construction), lower thermal load (~950 C flame temp), water-like viscosity, and common materials compatibility (aluminum, stainless steels, and most elastomers). CMP-X thrusters have demonstrated 180 s specific impulse at 174 mN thrust during thrust stand testing and continuous firing times > 10 min. Phase I demonstrated an improved catalyst for CMP-X with higher reactivity and longer life with minimal warmup time, enabling scaling to >500 mN. An earlier, slightly more concentrated formulation (CMP-8) has demonstrated shelf life exceeding 1200 days. Phase II studies will include long-duration CMP-X storage testing, UN/DOT Series 6 testing to establish a formal hazard classification of CMP-X (anticipated to be permitted on common commercial air transport such as UPS), further catalyst risk reduction studies / characterizations, and brassboard feed system development. CMP-X is designed not for highest performance Isp, but as a monopropellant option for customers who can accept a modest 20% performance penalty (relative to AF-315E and LMP-103S) for the advantages of lower cost, air transportability, considerably fewer range safety concerns, lower flame temperature resulting in considerably less thermal soakback into the spacecraft, and longer continuous thrust burns. The estimated total impulse of a 2U-sized flight MPUC is >2400 N-sec with a peak power draw of ~6 W and 180 s specific impulse.
MPUC responds to goals in NASA’s Roadmap for In-Space Propulsion with a focus on long life and cost reduction both with common COTS construction materials. MPUC has demonstrated performance that will yield volumetric impulse levels above those of legacy hydrazine systems. Its lack of detonation and demonstrated storability makes it a prime candidate for missions where costs and logistics are dominated by system transportation and range safety concerns. Potential missions include orbit change, drag makeup, and deorbiting.
Potential MPUC applications include drag makeup allowing extended-duration low altitude orbits, orbit raising, deorbiting for micro/nanosatellites, and/or deep space missions. The MPUC green monopropellant system offers affordable access to Cubesat propulsion and is easily scalable to larger sizes depending on mission requirements to meet needs of differing users in DOD, industry, and academia.