Space Propulsion: a Survey Study About Current and Future Technologies

Abstract

Current Space Launch Vehicles use chemical reactions (solid and liquid propellants) to achieve suffi cient thrust to launch artifacts and humans into space. Propulsion technologies can be framed in three different categories: “escape propulsion”, “in-space propulsion”, and “deep space propulsion”. The launch vehicles currently used for “escape propulsion” rely on mature technologies, which experienced only small incremental improvements over the last fi ve decades, and breakthroughs for this kind of propulsion are not foreseen for the next two decades. This research gathered information on the main operational heavy-lift space launch vehicles with capacity over 5,000 kg that are used to reach GEO (Geostationary Earth Orbit) by the United States, Russia, Europe, China, Japan and India and compared their thrust capability. The results show that performance was improved mainly by adding boosters, increasing gross propellant weight, with larger diameter rocket motors and using more effi cient liquid propellant pairs. Information regarding the frequency of published scientifi c articles and patents on Space Vehicles Propulsion Systems since the 1960s was also gathered, which demonstrates some progress in the last years, mainly in USA and Europe. “In-space” and “Deep space” spacecraft were also briefl y examined in this article, resuming the main features of some new promising developments, mainly regarding the latter, which present prospects of signifi cant technological advances; however, real progress in interplanetary missions will be possible only when technological breakthroughs towards other propulsion types become possible and feasible. So, two questions motivated the authors: why space propulsion development seems stagnant? Are there prospects for progress?