NERVA ROCKET ENGINE
The Nuclear Engine for Rocket Vehicle Application (NERVA) was a nuclear thermal rocket engine development program. Which runs for 2 decades. It was a joint NASA and Atomic Energy Commission endeavor to develop a nuclear-powered rocket for both long-range missions to Mars and as a possible upper stage for the Apollo Program. Nerva got its origin from Project Rover. An AEC research project at the Los Alamos Scientific Laboratory (LASL) initially aimed to provide a nuclear-powered upper stage for the United States Air Force intercontinental ballistic missiles.
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 space mission application”. Nuclear thermal rocket engines are 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. Nerva is a highly successful program that met or exceeded its program goals. NERVA 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.
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.
NERVA NRX
Nerva NRX was a prototype of a complete engine. That means it would need actuators to turn the drums and start the engine, gimbals to control its movement, a nozzle cooled by liquid hydrogen, and shielding to protect the engine, payload, and crew from radiation. The first test of a NERVA engine was of NERVA A2 on 24 September 1964. followed by the next test of A3 on 23 April 1965. This test was intended to verify that the engine could be run and restarted at full power. The engine was operated for eight minutes, three and a half of them at full power before the instruments indicated that too much hydrogen was going into the engine
NERVA XE
The second NERVA engine, the NERVA XE, was designed to come as close as possible to a complete flight system, even to the point of using a flight-design turbopump. To save time and money, components that would not affect the engine’s performance were selected from what was available at Jackass Flats. A radiation shield was added to protect external components.
With the success of the A6 test, SNPO canceled planned follow-on tests A7 and A8 and concentrated on completing ETS-1. All previous tests had the engine firing upwards; ETS-1 would permit an engine to be reoriented to fire downward into a reduced-pressure compartment to partly simulate firing in the vacuum of space. The test stand provided a reduced atmospheric pressure of about 6.9 kilopascals (1.00 psi) — equivalent to being at an altitude of 60,000 feet (18,000 m). This was done by injecting water into the exhaust, which created superheated steam that surged out at high speeds, creating a vacuum. The final test of the series was XE Prime. The final test of the series was XE Prime. This engine was 6.9 meters (23 ft) long, 2.59 meters (8 ft 6 in) in diameter, and weighed approximately 18,144 kilograms (40,001 lb). It was designed to produce a nominal thrust of 246,663 newtons (55,452 lbs) with a specific impulse of 710 seconds (7.0 km/s).
A series of experiments were carried out between 4 December 1968 and 11 September 1969, during which the reactor was started 24 times, and ran at full power for 1,680 seconds. At the time of the NERVA NRX/EST test, NASA’s plans for NERVA included a visit to Mars by 1978, a permanent lunar base by 1981, and deep space probes to Jupiter, Saturn, and the outer planets. NERVA rockets would be used for nuclear “tugs” designed to take payloads from low earth orbit (LEO) to higher orbits as a component of the later-named Space Transportation System, resupply several space stations in orbit around the Earth and Moon, and support a permanent lunar base.
