A nest for Blackbirds
Air-sampling data was taken almost daily at Watertown during 1958 and 1959 and intermittently in 1960. The airbase was revitalized during this period when it was selected to support the OXCART program, a predecessor of the Lockheed SR-71 Blackbird. In 1959, the base facilities were expanded to include a radar cross-section measurement range for use in developing the anti-radar capabilities of the OXCART airplane, known as the A-12. The decision to test the A-12 and train CIA pilots at Groom Lake meant that the base would not only have to be expanded, but almost entirely rebuilt. The expansion of the base included new hangars, dormitories, runways, and fuel storage facilities. By 1960, Watertown was commonly known as Area 51, a designation that would appear on most documents and maps for the next two decades.
The OXCART program operated at Area 51 from 1962 until 1968. This did not signal the demise of the remote airbase, however. Other CIA and Air Force programs sustained it for many decades. The Air Force took control of the site in 1977, and it has only continued to grow.
Shot SEDAN was part of the Plowshare program for peaceful uses of nuclear explosives. The device was buried at a depth of 635 feet to maximize its cratering potential. SEDAN exploded with a yield of 104 kilotons, blasting a crater 320 feet deep and 1,280 feet across in the sandy soil of Area 10 on Yucca Flat. Fallout from the shot drifted over Groom Lake.
The last completely above ground test at NTS took place on 17 July 1962. There were, however, several cratering tests conducted in support of Project Plowshare. This endeavor called for the use of nuclear explosives for excavation of canals, harbors, and mountain passes. To prove the feasibility of such peaceful uses of nuclear explosives, devices were buried at a depth that would allow the maximum amount of soil to be displaced.
Fallout and debris from cratering shots were hurled high into the atmosphere. The first cratering test was actually sponsored by the Department of Defense, and was not part of Plowshare. Called DANNY BOY, the 0.43-kiloton shot blasted an 84-foot deep, 265-foot wide crater in basaltic rock on 5 March 1962. Radioactivity was detected off-site, probably at Area 51 which was downwind. The largest cratering shot was SEDAN, on 6 July 1962. The 104-