NERVA · CANCELLED
NERVA
CONFIRMED · OFFICIAL
Nuclear Engine for Rocket Vehicle Application. The most advanced nuclear thermal rocket ever built and tested, NERVA achieved thrust levels and specific impulse far exceeding chemical rockets. Cancelled in 1972 despite successful tests.
NERVA (Nuclear Engine for Rocket Vehicle Application) was a joint NASA/Atomic Energy Commission program that produced the most powerful nuclear thermal rocket ever tested. Between 1959 and 1972, researchers at Los Alamos and Jackass Flats, Nevada conducted 28 engine tests, including the XE-Prime engine which ran for over an hour at full power. The program achieved specific impulse of 825 seconds — roughly double that of the best chemical rockets — making Mars missions a realistic near-term goal. President Nixon cancelled the program in 1972 as part of post-Apollo budget cuts, despite the technology working exactly as designed. The propellant, liquid hydrogen, was heated by a nuclear reactor core and expelled through a nozzle. No nuclear fuel was released during operation. Had the program continued, a crewed Mars mission by the 1980s was considered achievable.