NERVA

NERVA

NERVA XE in ETS-1
Country of origin	United States
Designer	Los Alamos Scientific Laboratory
Manufacturer	Aerojet (engine) Westinghouse (reactor)
Application	Upper stage engine
Status	Retired
Liquid-fuel engine
Propellant	Liquid hydrogen
Performance
Thrust, vacuum	246,663 N (55,452 lbf)
Chamber pressure	3,861 kPa (560 psi)
Specific impulse, vacuum	841 seconds (8.25 km/s)
Specific impulse, sea-level	710 seconds (7 km/s)
Burn time	1,680 seconds
Restarts	24
Dimensions
Length	6.9 m (23 ft)
Diameter	2.59 m (8 ft 6 in)
Dry weight	18,144 kg (40,001 lb)
Nuclear reactor
Operational	1968 to 1969
Status	Decommissioned
Main parameters of the reactor core
Fuel (fissile material)	Highly enriched uranium
Fuel state	Solid
Neutron energy spectrum	Thermal
Primary control method	Control drums
Primary moderator	Nuclear graphite
Primary coolant	Liquid hydrogen
Reactor usage
Power (thermal)	1,137 MW
References
References	[1]
Notes	Figures for XE Prime

The Nuclear Engine for Rocket Vehicle Application (NERVA; /ˈnɜːrvə/) was a nuclear thermal rocket engine development program that ran for roughly two decades. Its principal objective was to "establish a technology base for nuclear rocket engine systems to be utilized in the design and development of propulsion systems for space mission application".^[2] It was a joint effort of the Atomic Energy Commission (AEC) and the National Aeronautics and Space Administration (NASA), and was managed by the Space Nuclear Propulsion Office (SNPO) until the program ended in January 1973. SNPO was led by NASA's Harold Finger and AEC's Milton Klein.

NERVA had its origins in Project Rover, an AEC research project at the Los Alamos Scientific Laboratory (LASL) with the initial aim of providing a nuclear-powered upper stage for the United States Air Force intercontinental ballistic missiles. Nuclear thermal rocket engines promised to be more efficient than chemical ones. After the formation of NASA in 1958, Project Rover was continued as a civilian project and was reoriented to producing a nuclear powered upper stage for NASA's Saturn V Moon rocket. Reactors were tested at very low power before being shipped to Jackass Flats in the Nevada Test Site. While LASL concentrated on reactor development, NASA built and tested complete rocket engines.

The AEC, SNPO, and NASA considered NERVA a highly successful program in that it met or exceeded its program goals. It demonstrated that nuclear thermal rocket engines were a feasible and reliable tool for space exploration, and at the end of 1968 SNPO deemed that the latest NERVA engine, the XE, met the requirements for a human mission to Mars. The program had strong political support from Senators Clinton P. Anderson and Margaret Chase Smith but was cancelled by President Richard Nixon in 1973. Although NERVA engines were built and tested as much as possible with flight-certified components and the engine was deemed ready for integration into a spacecraft, they never flew in space.