DARPA's Demonstration Rocket for Agile Cislunar Operations (DRACO) program, in consultation with NASA, is an effort to advance nuclear propulsion technology for critical space missions.

Nuclear thermal rockets (NTRs) use a nuclear reactor to heat propellant to extreme temperatures before exhausting the hot propellant through a nozzle to produce thrust. Compared to conventional space propulsion technologies, NTRs offers a high thrust-to-weight ratio around 10,000 times greater than electric propulsion and two-to-five times greater specific impulse (i.e. propellant efficiency) than in-space chemical propulsion.

A leap-ahead propulsion technology would enable new mission sets – both in the cislunar domain and for trips to Mars and beyond.