Gaps, Challenges, and Successes in Green Propulsion

This paper reviews the current literature on green propulsion efforts with an emphasis on rocket propulsion systems. Solid, liquid, and hybrid rockets serve as the primary focus, as they are currently the most viable options for missions originating from the surface of the Earth; however, other propulsion systems are also considered. The tools and methods used in green propulsion research are identified and tools from other disciplines are introduced, where appropriate. Finally, gaps and challenges in the current state of the art are discussed to highlight areas for future research.