The Vela Incident

Looks like a small thing to cause a great deal of fuss, doesn't it?



The Vela satellites were designed to monitor nuclear testing, after the 1963 Nuclear Test Ban Treaty went into effect. From what I've been able to tell, they served a productive but relatively bland life, apparently doing their job without incident, and contributing to a significant astronomical discovery involving gamma-ray bursts.

Until they had almost reached the end of their lifespan...

In 1979, a Vela satellite detected a bright double-flash in the area of the Prince Edward Islands, about halfway between Antarctica and the south tip of Africa. The double-flash is characteristic of a nuclear explosion; but other tests performed at the time, including aerial sweeps for radioactive dust, came up negative. To this day, there is no authoritative answer to what happened; popular theories include a joint Israeli-South Africa nuclear test, an odd meteorite, a massive lightning strike, or just a faulty signal from aging equipment (the satellite was well over its expected 10-year lifespan). Whatever it was, it's interesting to read the amount of speculation in the Wikipedia article linked above!