Thermal nuclear propulsion is similar to chemical propulsion in that it achieves a boost by the force of reaction by ejecting very hot gas from a nozzle. However, instead of using chemical combustion, it uses nuclear fission (although in the future it could use nuclear fusion). The advantage of the nuclear route over the chemical one is that for the same weight it exerts a much greater push.
In a thermal nuclear rocket, a fission reactor is used to generate extremely high temperatures. The heat produced by the reactor is transferred to a liquid propellant, which expands and is expelled through a nozzle to propel the spacecraft. Thermal nuclear rockets can be three times more efficient than conventional chemical propulsion or even more.
NASA (US space agency) and DARPA (Defense Advanced Research Projects Agency, dependent on the US Department of Defense), have begun to collaborate on a demonstration of a thermal nuclear propulsion rocket in space. Such a rocket can greatly facilitate sending a manned spacecraft to Mars, among other things.
In this project, called DRACO (Demonstration Rocket for Agile Cislunar Operations), NASA and DARPA will work together to develop and demonstrate advanced nuclear thermal propulsion technology for spacecraft. The demonstration in space could take place within a few years, in 2027 if there are no delays.
Artist’s impression of the DRACO project vehicle, propelled into space by thermal nuclear propulsion. (Illustration: DARPA)
The use of a thermal nuclear rocket allows a shorter transit time, thanks to the higher speed it achieves. A shorter journey reduces the risk for astronauts. Reducing transit time is a key component for human missions to Mars, as longer journeys require more supplies and more robust systems to better withstand the test of time.
Other advantages of nuclear thermal propulsion for space travel include increased scientific payload capacity and increased electrical power for instrumentation and communications. (Font: NCYT de Amazings)