U.S. satellite developed to detect nuclear explosions.
Three types of Vela satellites were deployed: Vela Hotel satellites, orbited in pairs to detect explosions on earth; Vela Sierra, to spot atmospheric and space detonations; and Vela Uniform, to pick up vibrations from underground and underwater explosions. The Vela Hotel satellites were "parked" some 60,000 miles above the earth-roughly one-fourth the distance to the moon.
The first U.S. detections of nuclear weapons from space were made by the Explorer 4 satellite, which detected five U.S. high-altitude nuclear tests in 1958. The Explorer 4, launched on July 26, 1958, was a radiation research satellite. Additional tests of monitoring equipment were carried out with Discoverer series satellites.
On Oct. 17, 1963, the first pair of Vela Hotel satellites was placed in orbit. Each satellite launched on the same Atlas-Agena D booster rocket-weighed 485 pounds. The gamma rays and neutron detectors in the satellites could detect a nuclear detonation as small as ten kilotons as far as 100 million miles from earth. The sensors could also measure solar flares, lightning, and radiation from sources other than nuclear explosion.
Vela launches continued, with improvements being made to their sensors. The last pair-Vela 11 and Vela 12-was orbited on April 8, 1970. Subsequently, satellites of the DSP program were fitted with nuclear detectors.
The Vela satellites detected nuclear detonations by the Soviet Union and China as well as other countries. They also made highly useful observations of natural phenomena.
Vela is Spanish for "watchman."
(Prior to the Vela satellites, the principal means of detecting nuclear detonations outside the United States was by aircraft fitted to collect fallout from explosions. A modified B-29 Superfortress collected radioactive material from the first Soviet nuclear detonation on Sept. 3, 1949, over the Sea of Japan. The bomb had been detonated in the Kazakh Desert on Aug. 25. Later, U-2 spyplanes were used in this role.)
