FOIA: Possible origins of optical data for the the 22 Sep 1979 Vela satellite event, page 1

Initial Notes

1. Many illustrations in the document are redacted;

2. Useful illustration of the subject of this document appears on page 52;

3. The satellite discussed is/was pointed at Earth and was specifically designed to detect nuclear explosions. It was one of a series of such satellites placed in orbit to monitor nuclear compliance.

Summary

On September 22, 1979, a VELA satellite received optical data possibly indicating a nuclear explosion. Two optical sensors were discussed: YC and YV. The data might also be interpreted as non-nuclear in origin and such sources are discussed later in the document.

Speculation early in the document stated that one of the two optical sensors may have been malfunctioning, as one sensor indicated a ground burst and the other indicated an air burst. Surface bursts yield lower silicon values than air bursts. It is assumed that soil and other surface debris cool the fireball thereby reducing silicon yield in a surface burst. The authors concluded that it was the YC sensor that malfunctioned.

After some discussion regarding interpretation of sensor data versus historical data, the document's authors concluded that, if the event was nuclear in origin, the source was a surface burst.

Two non-nuclear sources were considered and discussed:

1. "Superbolt" lightning ("100 times more powerful than 'typical' lightning"; more common in the maritime environment);

2. Sunlight reflected onto the sensors by nearby objects.

The authors stated that superbolt lightning was a possibility because the data fell within the parameters for that type of event, but did not appear convinced that this was the likely explanation.

Their discussion of "solar irradiance" or reflected sunlight was extensive and they concluded the following:

1. The reflecting object had an irregular, unusually reflective surface, speculating that one surface in particular may have been specifically "tailored to mimic a bomb";

2. May have been a truncated sphere one millimeter in size;

3. Probably not satellite debris based on its speed and trajectory: It appeared to approach the satellite from behind at a distance of one to ten meters and passed between the two sensors in less than half a second.

Supplemental

Internet research indicates that later astrophysical research determined this incident was one of the first detected gamma ray bursts.

[edit on 11/24/2007 by PrplHrt]