When we think about nuclear energy, we think of power and submarines, not reaching the outer limits of the galaxy. Nuclear thermal energy, however, is a promising technology for space exploration, especially missions to Mars. According to a report by the National Academies of Sciences, Engineering, and Medicine, nuclear thermal propulsion (NTP) could be a viable means of propulsion for a human mission to Mars in 2039. NASA has been exploring NTP since the 1960s, and it is considered to be the only realistic path for humans to reach Mars.
A nuclear thermal propulsion system uses a nuclear reactor to generate heat, which is then used to heat a propellant such as hydrogen to produce thrust. This type of propellant system is typically used for in-space propulsion systems that rely upon a low molecular weight fuel that flows through a reactor to generate heat due to the nuclear fission processes and eventual thrust. The use of nuclear thermal propulsion systems could significantly reduce travel times and carry greater payloads than today’s top chemical rockets, giving humans a great chance of exploring deep space.
While there are also challenges, including safety concerns, development costs, and public perception of nuclear propulsion systems, nuclear thermal propulsion remains an attractive option for certain space exploration scenarios. NASA and other space agencies have explored the concept, and research continues to advance the technology.