Nuclear Thermal Propulsion for Space

Nuclear thermal propulsion (NTP) uses a nuclear reactor to heat propellant (hydrogen) to extremely high temperatures, producing thrust with twice the efficiency (specific impulse) of conventional chemical rockets. DARPA's Demonstration Rocket for Agile Cislunar Operations (DRACO) program, partnering with Lockheed Martin and BWX Technologies, aims to fly a nuclear thermal rocket engine in space by 2027.

NTP is the enabling technology for practical crewed Mars missions. Chemical propulsion requires 9-month transit times each way, exposing astronauts to dangerous radiation and microgravity effects. NTP cuts this to 3-4 months, dramatically reducing biological risk and logistics requirements. The technology also enables rapid repositioning of military assets in cislunar space.

The US previously tested nuclear thermal engines in the 1960s-70s (NERVA program) but abandoned development. DARPA's DRACO program revives this capability with modern materials and reactor design. China is also developing NTP, creating a space race dynamic for technologies that enable deep space operations.