FY18-C2 GRC: Green Propulsion Catalyst Test Article

Green propulsion offers improved performance and reduced toxicity concerns over state-of-the-art hydrazine propulsion systems, and green propellants are being sought for the next generation of monopropellant systems for future missions. Several potential thruster systems and propellants are in development by commercial entities already. While some systems have seen flight demonstrations, there has been limited adoption and there are still numerous technical gaps to be identified and resolved before green propulsion will reach a maturity level where mission planners feel comfortable with more widespread use of these propulsion systems. One recognized technical gap is in the catalyst systems, which are required in the monopropellant thrusters for combustion of the propellant. Green propellants when combusted produce hotter, more corrosive environments than hydrazine-based systems, and this environment tends to limit the life of state-of-the-art catalyst systems. These catalyst systems also need significant preheat to make them suitable for use with green propellants. Catalyst life limitations have already been seen in various commercial systems in development. A modular, workhorse test article could be used to test different catalyst & injector configurations, test different pre-heating schemes, and support modeling efforts by anchoring models with test data, all needs identified in the 2018 NASA Green Propulsion Technology Development Roadmap (NASA/TP—2018–219861). The primary goal of this project is to develop workhorse hardware, suitable for testing various catalyst systems for green propulsion, which can be utilized by NASA to enhance green propulsion technology development efforts.

Green propulsion as a hydrazine replacement is an area of interest in the commercial market and government agencies. Several large commercial vendors have developed product lines or partnerships to deliver green propulsion thruster systems. Additionally, a number of small business entities have also conducted or expressed interest in developing green propulsion technologies. However, most development efforts have focused around commercializing product lines. Thus, limited design details are shared under the various partnership efforts, as many details are considered proprietary. In order to better understand the technology and to support public-private partnership efforts, NASA needs design-agnostic tools to independently evaluate and assess various technology component solutions. A modular, workhorse test article that is not dependent on proprietary catalyst or chamber designs would be enhancing to support any NASA funded or public-private partnership efforts. A modular test article could help explore new and emerging catalyst systems, which when sufficiently matured could bring green propulsion to a tipping point of technical maturity and component cost that would enable adoption into future NASA missions. Testing, such as under public-private partnerships, could help explore design features that are otherwise ignored under tight IR&D budgets and the rush to get a mature product to market, thus providing more insight and understanding for the broader community as a whole. In the near- to mid-term, defined as 5-10 years, the 1-N to 22-N class of thruster can be studied. Better understanding catalyst life is one aspect to be explored in this timeframe, which would be enhancing towards initial mission adoption. As lessons are learned in this class, and systems are scaled up, more enabling advancements could be seen at larger classes (>22-N) and aeronautical applications (such as auxiliary power units, APUs) in the next 10-20 years.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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