Green Propulsion Advancement: Challenging the Maturity of Monopropellant Hydrazine

Recent commercial and government investments have resulted in substantial advances in the technology readiness of a number of new candidate “green” monopropellants, many of which have already completed, or will complete in the next few years, successful on-orbit demonstrations. These propellants are often touted as potential (and in some cases technology-level ready) replacements for conventional hydrazine. This paper presents a comprehensive, carefully considered set of screening criteria, against which will be evaluated a number of these emergent candidates alongside flight-proven propellants. Thereafter, a thorough assessment of both the performance advantages and disadvantages, as well as current states of the art (and technology readiness levels) for a number of these emerging green technologies as compared with each other and incumbent hydrazine flight systems are provided. Additional discussion is included addressing what it notionally means for a propellant to be green, how definitions vary throug...