4.4 OPERATION RANGER. Operation RANGER was the first atmospheric nuclear weapons test series conducted by the Atomic Energy Commission at the Nevada Test Site. This 1951 series consisted of five nuclear events, all of which were airdrops detonated at heights of about 1,000-1,400 feet. In addition, RANGER included one non- nuclear high-explosive test detonated 2 days before the first nuclear event. The following table provides specifics on the nuclear shots (6: 1,4): 4.4.1 Event Date Type Yield ABLE 27 January Airdrop 1 BAKER 28 January Airdrop 8 (kilotons) EASY 1 February Airdrop 1 BAKER-2 2 February Airdrop 8 FOX 6 February Airdrop 22 Background and Objectives of Operation RANGER. In November 1950, the Los Alamos National Laboratory discovered that insufficient data were available to determine satisfactory design criteria for nuclear devices to be tested in Operation GREENHOUSE, a series of AEC nuclear tests scheduled for the Pacific from 7 April through 24 May 1951. The LANL scientists believed that variations in the compression of the critical material could affect the yields of the GREENHOUSE devices. To confirm this hypothesis, LANL held conferences on 6 and 11 December 1950 and concluded that a series of small nuclear tests should be conducted to improve the GREENHOUSE design criteria. On 22 December 1950, LANL requested approval for a conti- nental series from the AEC Division of Military Application (DMA). DMA approved the request and asked for Presidential approval to expend the fissionable material required for the series and to use part of the Las Vegas Bombing and Gunnery Range in Nevada for the tests. The White House responded affirmatively to both requests on 11 January 1951, formally creating Operation RANGER (6: 18). 80