Editing Project Pluto (section)

==Origins==
During the 1950s, the [[United States Air Force]] (USAF) considered the use of [[nuclear powered aircraft]] and missiles as part of its [[Aircraft Nuclear Propulsion]] project, which was coordinated by the Aircraft Nuclear Propulsion Office.{{sfn|Gantz|1960|p=16}} Research into missiles was coordinated by its Missile Projects Branch.{{sfn|Gantz|1960|p=28}}  The concept of using a [[nuclear reactor]] to provide a heat source for a [[ramjet]] was explored by [[Frank E. Rom]] and Eldon W. Sams at the [[National Advisory Committee for Aeronautics]] [[Lewis Research Center]] in 1954 and 1955.<ref>{{cite report |last=Rom |first=Frank E. |title=Analysis of a Nuclear-Powered Ram-Jet Missile |publisher=National Advisory Committee for Aeronautics |id=NACA-RM-E54E07 |date=October 1954 |url=http://large.stanford.edu/courses/2015/ph241/rossi1/docs/rom.pdf |access-date=7 April 2022 |archive-date=9 April 2022 |archive-url=https://web.archive.org/web/20220409170249/http://large.stanford.edu/courses/2015/ph241/rossi1/docs/rom.pdf |url-status=live }}</ref><ref>{{cite report |last1=Sams |first1=Eldon W. |last2=Rom |first2=Frank E. |title=Analysis of Low-Temperature Nuclear-Powered Ram-Jet Missile for High Altitudes |publisher=National Advistory Committee for Aeronautics |id=NACA-RM-E55G21 |date=November 1955 |url=https://ntrs.nasa.gov/api/citations/19930088872/downloads/19930088872.pdf?attachment=true |access-date=7 April 2022 |archive-date=31 May 2022 |archive-url=https://web.archive.org/web/20220531235430/https://ntrs.nasa.gov/api/citations/19930088872/downloads/19930088872.pdf?attachment=true |url-status=live }}</ref> The principle behind the nuclear ramjet was relatively simple: motion of the vehicle pushed air in through the front of the vehicle (the ram effect). If a nuclear reactor heated the air, the hot air expanded at high speed out through a nozzle at the back, providing thrust.<ref name="fact sheet" />

At the time, the [[United States Atomic Energy Commission]] (AEC) was conducting studies of the use of a nuclear rocket as an upper stage of an [[intercontinental ballistic missile]] (ICBM) on behalf of the USAF. The AEC farmed this work out to its two rival atomic weapons laboratories, the [[Los Alamos Scientific Laboratory]] (LASL) in [[Los Alamos, New Mexico]], and the [[Lawrence Radiation Laboratory]] at [[Livermore, California]]. By late 1956 improvements in nuclear weapon design had reduced the need for a nuclear upper stage, and the development effort was concentrated at LASL, where it became known as [[Project Rover]].{{sfn|Hacker|1995|pp=85–86}}

On 1 January 1957, the USAF and the AEC selected the Livermore Laboratory to study the design of a nuclear reactor to power ramjet engines.{{sfn|Herken|1990|pp=28–34}} This research became known as Project Pluto.<ref name="fact sheet" /> It was directed by Theodore C. (Ted) Merkle, leader of the Laboratory's R Division.{{sfn|Herken|1990|pp=28–34}}