The National Academy of Sciences, Engineering and Medicine has produced a report — commissioned by NASA — which lays out a pathway for the United States to begin human exploration of the Solar System beyond the lunar orbit. Stopping just short of mandating nuclear propulsion, the report, “Space Nuclear Propulsion for Human Mars Exploration,” makes clear that current modes of chemical propulsion are inadequate and that therefore a breakthrough is necessary. https://www.nationalacademies.org/news/2021/02/for-humans-to-reach-mars-advances-are-needed-in-space-nuclear-propulsion-technologies
“NASA should commit within the year to conducting an extensive and objective assessment of the merits and challenges of using different types of space nuclear propulsion systems,” reads the press release, “and to making significant technology investments this decade. Such a program must include subsystem development, prototype systems, ground testing, and cargo missions as a means of flight qualification prior to first crewed use.”
While fission energy for space propulsion is less capable than a system that uses fusion power (increased energy density), a fission drive would provide an incremental increase in propulsion efficiency as compared to today’s chemical rockets. NASA has started and stopped a half-dozen space nuclear power projects, needed for manned deep space travel since the 1960s.
While not (yet) addressing the question of fusion propulsion, the report—a 104-page “consensus report” of the NAS’s Aeronautics and Space Engineering Board’s Space Nuclear Propulsion Technologies Committee — “assesses the primary challenges, merits, and risks for developing a nuclear electric propulsion (NEP) system and a nuclear thermal propulsion (NTP) system for a human mission to Mars.”
NASA has the official goal—announced in 2015—of sending a four-person crewed mission to Mars, launching in 2039. Bobby Braun, director for planetary science at the Jet Propulsion Laboratory and co-chair of the committee that wrote the report, said, “Space nuclear propulsion technology shows great potential to facilitate the human exploration of Mars. However, significant acceleration in the pace of technology maturation is required if NASA and its partners are to complete this mission within the stated timeline.”
