John Stockton

Vela Satellites were placed in high orbits to avoid the Van Allen radiation belt

New Scientist 6th February 1975 (continued)

 Pages 313 to 315 of issue 935 features Cosmic gamma-ray bursts by Dr Andrew Fabian and Dr James Pringle. “ Transient phenomena are becoming a natural aspect of high-energy astrophysics. In recent months short bursts of gamma rays have been observed from a number of space platforms, leaving theorists perplexed- although not altogether tongue-tied – as to their origin”

In 1975 mysterious bursts of gamma rays lasting about ten seconds emanating from space were mysterious as no known astronomical objects were known to be located at their points of origin. The open question was made more intriguing by the accidental nature of their discovery. The 1963 Partial Test Ban Treaty forbade the atmospheric (surface) testing of nuclear and thermonuclear weapons, and five Vela satellites were placed in Earth orbit to detect gamma rays from any clandestine explosions. As soon as the satellites registered gamma rays the events would have been taken very seriously.

Although the satellites were launched one week after the implementation of the treaty it was ten years before the detection of the Gamma ray bursts was revealed. “R.W. Klebesadel, I.B. Strong and R.A. Olson of the Los Alamos Scientific Laboratory announced the discovery of the first 16 cosmic gamma-ray bursts in 1973. Since then another eight or so have been reported, as well as other sightings of several bursts by detectors on OGO-3, IMP-6, OSO-7 and the Apollo16. This last system, in the Apollo 16 command module, was designed for determining lunar surface composition by by fluorescence techniques.”

By triangulating from the arrival times of the gamma ray bursts at different satellites, it was initially determined that they emanated from beyond the solar system and the burst that was detected by satellites as well as the Apollo 16 astronauts orbiting the moon was traced to region away from the plane of the Milky Way and close to the Small Magellanic Cloud. From the perspective of 1975, the mystery surrounding gamma ray bursts was compounded by the lack of data. The success of triangulation from the arrival times of bursts at the positions of different satellites was limited by timing errors, which resulted in the search zones 15 degrees wide. Theories ranged from comets plunging into neutron starts, through star quakes and super flares, to nuclear holocausts resulting from global warfare on alien planets.