For Immediate Release - March 1, 2001


1979 South Atlantic "Flash" is Consistent with a Nuclear Explosion, According to Newly Declassified Energy Department Documents
Findings dispute public explanation offered by Presidential panel
at the time of the event

For further information, contact:
David Albright, President or
Corey Gay Hinderstein, Policy Analyst,
(202) 547-3633

On September 22, 1979, the U.S. Vela satellite detected a mysterious signal in the South Atlantic. First, U.S. scientists speculated that the signal showed that South Africa had conducted a secret nuclear explosion. Later, officials asserted quietly that the test could have been an Israeli nuclear weapons test with South African knowledge or collusion.

A scientific panel convened by the Carter administration concluded in early 1980 that the "September 22 signal was probably not from a nuclear explosion." (1) Although the panel could not rule out the possibility of a nuclear origin for the signal, the panel "considers it more likely that the signal was one of the zoo events, possibly a consequence of the impact of a small meteroid on the satellite."

In response to the Carter Administration panel, scientists at Los Alamos National Laboratory (LANL) in New Mexico attempted to explain the signal in the context of a particular model of nuclear explosions. Their results are described in the newly declassified, but heavily redacted, study, titled "Low Yield Nuclear Explosion Calculations: The 9/22/79 Vela Signal," originally published in 1982. The report states:
"We have constructed what we believe to be a plausible model for a low-yield nuclear explosion that could have produced the observed Alert 747 signal [the 1979 Vela signal]."

The abstract of the LANL document states:

Normally, independent confirming evidence is available from other Vela satellites and other sources. Unfortunately, such confirming evidence has not been uncovered for the 9/22/79 event…We summarize the Vela data, discuss classical interpretations and present a particular model which, we believe, satisfactorily reproduces the Vela signal…Our model is consistent with the apparent absence of nuclear debris, the collection of which is required by some analysts for absolute confirmation of an atmospheric detonation.

The study acknowledges that the signal was not typical. "Clearly, conventional scaling laws cannot provide a consistent model for the Vela data," the report states.

"This document provides support for those who conclude that a nuclear explosion occurred south of South Africa in September 1979," said David Albright, President of ISIS. "It also confirms the importance of declassifying more information about this possible nuclear test," he added. Clearly, the Vela signal was hotly debated in the secret hallways of the U.S. government for years after the event. "It is time to let the public in on this debate," he said.

The documents were released in January 2001 in response to a request filed under the Freedom of Information Act by the Institute for Science and International Security (ISIS) more than three years ago. The documents are heavily redacted, with exemptions for "atomic energy" and "national security" secrets throughout.

Another document was also declassified. This document, titled "A Method for Automated Recognition of Satellite Radiometric Waveforms (U)," is so heavily redacted that it is unclear what relation it has to the September 22, 1979 event. We know it has some relation, however, because we were informed prior to Energy Department's classification review that we may find it interesting.

The Institute for Science and International Security is a non-profit, non-partisan research institution based in Washington, DC.

(1) Executive Office of the President, Office of Science and Technology Policy, "Ad Hoc Panel Report on the September 22 Event," 1980.

The recently declassified documents can be downloaded in Adobe Acrobat form here:

Low Yield Nuclear Explosion Calculations: The 9/22/79 Vela Signal

A Method for Automated Recognition of Satellite Radiometric Waveforms (U)

** To download Acrobat reader click here



Albright and Hinderstein wrote about the South Atlantic "flash" in The Bulletin of the Atomic Scientists in the November/December 1997 issue. For a copy of the article go here, or contact ISIS.