GREEN PROPULSION TECHNOLOGIES FOR SUSTAINABLE SPACE MISSIONS: A MISSION-ORIENTED REVIEW

Abstract

While hydrazine is the reference propellant for many spacecraft reaction-control and orbit-maintenance systems today, its toxicity, handling burden and regulatory pressure have driven a search for safer alternatives. In line with this, the review in this paper gives a mission-oriented comparison of green spacecraft propulsion options. The reviewed literature is published from 2000 to May 2026, which are identified using major databases, agency reports, conference papers and also selected flight-heritage sources. The discussion covers ADN/LMP-103S, HAN/ASCENT, high-test peroxide, nitrous-oxide systems, green hybrid and bipropellant concepts and electric propulsion using iodine or krypton. The comparison uses specific impulse, density impulse, storage behavior, catalyst or ignition needs, thermal and material limits, toxicity, maturity, cost implications and mission suitability. On the whole, it is found that ADN and HAN monopropellants appear to be the most practical near-term chemical replacements for many hydrazine applications. Meanwhile, HTP and nitrous-oxide systems are useful where the safety and simpler operations matter more than peak performance. Furthermore, iodine and krypton electric propulsion are not direct hydrazine substitutes for impulsive maneuvers but they can reduce the reliance on xenon in low-thrust missions. The main remaining barriers are catalyst durability, high-temperature materials, storage qualification, repeatable starts and system-level flight verification.