NERVA
In 1946, Stan Ulam and C. J. Everett wrote a paper considering the use of atomic bombs as rocket propulsion at Los Alamos Laboratory. This document became the basis for Project Orion, though it remained classified Restricted Data. The public revelation of atomic energy after World War II generated speculation about nuclear-powered rockets in the United Kingdom. Val Cleaver, chief engineer at De Havilland, and Leslie Shepherd, a nuclear physicist at Cambridge University, independently considered the problem. They collaborated to outline designs for solid-core graphite heat exchangers in papers published in the Journal of the British Interplanetary Society during 1948 and 1949. Their work concluded that while essential for deep space exploration, such technology was not yet technically feasible.
Robert W. Bussard wrote a detailed study titled Nuclear Energy for Rocket Propulsion in 1953 while working on the NEPA project at Oak Ridge National Laboratory. Only 29 copies were printed initially, limiting its circulation among those with security clearance. Darol Froman, deputy director at Los Alamos Scientific Laboratory, and Herbert York, director of the University of California Radiation Laboratory at Livermore, established committees to investigate nuclear rocket propulsion. John von Neumann formed an ad hoc committee for missile propulsion, chaired by Mark Mills. Norris Bradbury from LASL, Edward Teller and Herbert York from Livermore, Abe Silverstein from NACA Lewis Flight Propulsion Laboratory, and Allen F. Donovan from Ramo-Wooldridge participated. The committee recommended proceeding in March 1955 to produce a nuclear rocket upper stage for intercontinental ballistic missiles. The Armed Forces Special Weapons Project allocated $100 million over three years in March 1956 for feasibility studies and test facility construction.
Project Rover began as an Atomic Energy Commission research project at Los Alamos Scientific Laboratory with the aim of providing a nuclear-powered upper stage for United States Air Force intercontinental ballistic missiles. Lieutenant Colonel Harold R. Schmidt directed the program under USAF oversight. Colonel Jack L. Armstrong managed both Project Rover and Project Pluto, which developed nuclear ramjets. By October 1958, responsibility for non-nuclear components transferred from the USAF to NASA on the day NASA officially became operational. Donald A. Quarles met with NASA Administrator T. Keith Glennan and Deputy Hugh Dryden on the 20th of August 1958, making Rover the first item on their agenda.
The Space Nuclear Propulsion Office formed on the 29th of August 1960, to oversee the joint NASA-AEC project. Harold Finger served as manager while Milton Klein acted as deputy director. SNPO headquarters co-located with AEC Headquarters in Germantown, Maryland. Branch offices opened in Albuquerque, New Mexico, and Cleveland, Ohio, by late 1963. Eight companies submitted bids for NERVA development contracts scheduled for the 1st of March 1961. Aerojet and Westinghouse won selection after James E. Webb intervened to combine bids. By 1963, Westinghouse employed 1,100 staff working on NERVA. The formal agreement between NASA and AEC regarding management of nuclear rocket engine contracts was signed the 1st of February 1961.
The Kiwi program named itself after the flightless New Zealand kiwi bird, reflecting its role as a non-flyable test engine. Three reactors built during the Kiwi A series tested between July 1959 and October 1960 proved hydrogen could be heated in a nuclear reactor to required temperatures. Kiwi B1A commenced testing the 7th of December 1961, developing improvements over earlier models. The second test, Kiwi B1B on the 1st of September 1962, caused extreme structural damage when ramped up to full power. Fuel module components ejected due to vibrations induced during heating rather than operation at full power.
Kennedy visited Los Alamos Scientific Laboratory the 7th of December 1962, becoming the first president to tour a nuclear weapons laboratory. He brought Lyndon Johnson, McGeorge Bundy, Jerome Wiesner, Harold Brown, Donald Hornig, Glenn Seaborg, Robert Seamans, Harold Finger, Clinton Anderson, Howard Cannon, and Alan Bible. The next day they flew to Jackass Flats, making Kennedy the only president to visit a nuclear test site. Project Rover received $187 million in 1962 while AEC and NASA requested another $360 million for 1963. Senator Anderson became chairman of the Senate Committee on Aeronautical and Space Sciences in January 1963. The Kiwi B4D test on the 13th of May 1964, showed automatic startup with no vibration problems. Subsequent tests demonstrated reactors could be shut down and restarted successfully.
NERVA NRX adopted the Kiwi-B4 design as its baseline with a specific impulse of 825 seconds. Westinghouse modified cores to make them more robust for flight conditions. New temperature sensors accurate up to 2,500 degrees Kelvin replaced older models limited to lower ranges. Aerojet and Westinghouse theoretically predicted component performance before comparing results against actual test data. By 1972, engineers could accurately forecast engine performance under most conditions.
The first NERVA engine test occurred the 24th of September 1964, when NERVA A2 ran flawlessly at full power of 1,096 MW. It operated for only 40 seconds because hydrogen supply ran out. Executives took out a full-page advertisement in the Wall Street Journal showing the test with the caption On to Mars! The reactor restarted October 15 to test turbopumps instead of nozzles. Power reached 40 MW while control drums locked in place. Turbopumps maintained steady power perfectly. Computer simulations proved correct as the project advanced ahead of schedule. The next test involved NERVA A3 on the 23rd of April 1965, verifying restart capability at full power despite coolant line clogging issues.
Work commenced on test facilities at Jackass Flats mid-1957 requiring all materials shipped from Las Vegas. Test Cell A featured concrete walls thick enough to protect electronic instrumentation from radiation produced by reactors. Control rooms located far away ensured operator safety. Reactors fired plumes into air so radioactive products dissipated safely. The reactor maintenance and disassembly building measured long, wide, and high, allowing engines moved via railroad car.
The Jackass and Western Railroad described itself as world shortest and slowest. Two locomotives served operations: remotely controlled electric L-1 and manually controlled diesel/electric L-2 with radiation shielding around cab. Construction workers housed in Mercury, Nevada before thirty mobile homes created Boyerville village named after supervisor Keith Boyer. Completion occurred fall 1958. NASA planned developing a community of 2,700 people with 800 dwellings and shopping complex by 1967. Test Cell C became operational 1964 after delays forced Senator Anderson intervention personally assuming de facto construction manager role. Giant cryogenic storage dewars constructed by Chicago Bridge & Iron Company held hydrogen for testing.
Richard Nixon replaced Johnson as president the 20th of January 1969, making cost cutting order of day. NASA program funding reduced by Congress shutting down Saturn V production line. Apollo 20 cancellation announced the 4th of January 1970 to make Saturn V available launching Skylab. Apollo 18 and 19 cancellations followed September 1970. Klein endorsed plan where Space Shuttle lifted NERVA engine into orbit then returned with fuel and payload. NERVA received $88 million fiscal year 1970 and $85 million FY 1971 from joint NASA-AEC funds.
Office of Management and Budget recommended cancelling NERVA and Skylab December 1970 fearing up to 20,000 job losses mostly in California. Nixon decided keep it alive low funding level canceling Apollo 17 instead. When Nixon tried killing NERVA 1971, Senators Anderson and Margaret Chase Smith killed Boeing 2707 supersonic transport project instead. This stunning defeat occurred despite budget requests only $17.4 million while Congress allocated $69 million. Nixon spent just $29 million of allocated funds. Congress supported NERVA again 1972 bipartisan coalition headed by Smith and Cannon appropriated $100 million for small engine fitting inside shuttle cargo bay estimated costing about $250 million over decade. Administration decided cancel anyway the 5th of January 1973 when NASA announced termination.
In 1983 Strategic Defense Initiative identified missions benefiting from rockets more powerful than chemical ones. Nuclear propulsion project SP-100 created February 1983 aiming developing 100 KW nuclear rocket system incorporating particle pebble-bed reactor concept developed by James R. Powell at Brookhaven National Laboratory. Proposed rocket transferred Space Nuclear Thermal Propulsion program Air Force Phillips Laboratory October 1991 after spending $139 million as secret Project Timber Wind between 1987 and 1991.
NASA conducted studies part of 1992 Space Exploration Initiative but felt SNTP offered insufficient improvement over NERVA not required any SEI missions. Program terminated January 1994 after $200 million spent. Engine studied March 2013 at Marshall Space Flight Center focusing on nuclear thermal rocket engines allowing quicker transfer times increasing cargo capacity. Shorter flight duration estimated three to four months compared eight to nine months using chemical engines reduced crew exposure harmful cosmic rays. Congress approved $125 million funding the 22nd of May 2019 for development nuclear thermal propulsion rockets. Seattle-based firm Ultra Safe Nuclear Technologies delivered design concept employing high-assay low-enriched uranium ZrC-encapsulated fuel particles the 19th of October 2020. NASA and Defense Advanced Research Projects Agency announced collaboration January 2023 testing engine space develop capability crewed missions Mars.
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Common questions
What was the NERVA nuclear thermal rocket engine project?
NERVA was a US Nuclear thermal rocket engine project that ran from 1956 to 1973. The program aimed to develop nuclear-powered upper stages for intercontinental ballistic missiles and later for space exploration missions.
When did the NERVA nuclear thermal rocket engine project officially begin?
The Armed Forces Special Weapons Project allocated $100 million over three years in March 1956 for feasibility studies and test facility construction. This funding marked the official start of the NERVA nuclear thermal rocket engine project timeline.
Where were the primary test facilities for the NERVA nuclear thermal rocket engine located?
Work commenced on test facilities at Jackass Flats mid-1957 requiring all materials shipped from Las Vegas. Test Cell A featured concrete walls thick enough to protect electronic instrumentation from radiation produced by reactors.
Why was the NERVA nuclear thermal rocket engine project cancelled in 1973?
Administration decided cancel anyway the 5th of January 1973 when NASA announced termination. Nixon spent just $29 million of allocated funds despite Congress supporting NERVA again 1972 bipartisan coalition headed by Smith and Cannon appropriated $100 million for small engine fitting inside shuttle cargo bay estimated costing about $250 million over decade.
How long would a crewed mission to Mars take using the NERVA nuclear thermal rocket engine compared to chemical engines?
Shorter flight duration estimated three to four months compared eight to nine months using chemical engines reduced crew exposure harmful cosmic rays. Engine studied March 2013 at Marshall Space Flight Center focusing on nuclear thermal rocket engines allowing quicker transfer times increasing cargo capacity.