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Orthographic projection centered on the Prince Edward Islands, the location of the Vela incident

The Vela Incident (sometimes referred to as the South Atlantic Flash) was an unidentified "double flash" of light that was detected by an American Vela Hotel satellite on September 22, 1979.

Some specialists who examined the data speculated that the double flash, characteristic of a nuclear explosion, may have been the result of a nuclear weapons test: "The conclusions of the Presidential panel (the Ad Hoc Panel) were reassuring, as they suggested that the most likely explanation of the Vela detection was a meteoroid hitting the satellite — in part because of the discrepancy in bhangmeter readings. Others who examined the data, including Defense Intelligence Agency (DIA), the national laboratories, and defense contractors reached a very different conclusion — that the data supported the conclusion that on 22 September 1979, Vela 6911 had detected a nuclear detonation."[1][2][3]

However, it has never been ruled out that the "double flash" signal might have been a spurious electronic signal that was generated by an aging detector in an old satellite. No corroboration of an explosion, such as the presence of nuclear wastes in the air, was ever made, although there were numerous passes in the area by U.S. Air Force planes that were specifically designed to detect airborne radioactive dust.

It was also noted that some meteoroids as they enter the atmosphere produce explosive bursts measured from several kilotons of TNT (the Eastern Mediterranean Event) to megatons of TNT (the Tunguska Event). However in such cases the physical manifestations are normally distinct from those that were observed, since single meteors do not produce the double flash characteristic of a nuclear detonation.



The "double flash" was detected on September 22, 1979, at 00:53 GMT, by the American Vela Hotel satellite 6911, which carried various sensors that had been designed specifically to detect nuclear explosions. In addition to being able to detect gamma rays, x-rays, and neutrons, the satellite also contained two silicon solid-state bhangmeter sensors that would be able to detect the dual light flashes associated with a nuclear explosion—to be specific the initial brief, intense flash, followed by the second longer flash.[2]

The satellite reported the characteristic double flash of an atmospheric nuclear explosion of two to three kilotons, in the Indian Ocean between Bouvet Island (a very small, uninhabited Norwegian possession) and the Prince Edward Islands which belong to South Africa at 47°S 40°E / 47°S 40°E / -47; 40Coordinates: 47°S 40°E / 47°S 40°E / -47; 40. Early technical speculation also examined the possibility that the Vela had recorded a combination of natural phenomena, such as lightning in conjunction with a meteor strike. Other early news media articles of the time discussed the possibility of a large object strike, such as an asteroid, occurring.[4]

Vela-5A/B Satellites in Clean Room. The two satellites are separated after launch.

There is much doubt[5] as to whether the satellite's observations were accurate. The Vela Hotel 6911 satellite was one of a pair that had been launched on May 23, 1969, over ten years before the "double-flash" event, and this satellite was already more than two years beyond its so-called "design lifetime". This satellite was known to have a failed electromagnetic pulse (EMP) sensor, and it had developed a fault (in July 1972) in its recording memory, but that fault had cleared itself by March 1978.

The initial assessment by the National Security Council (NSC) in October 1979[6] was that the American intelligence community had "high confidence" that the event was a low-yield nuclear explosion, although no radioactive debris had ever been detected, and there was "no corroborating seismic or hydro-acoustic data."[6] A later NSC report revised this position to "a position of agnosticism" about whether a test had occurred or not.[7] The NSC concluded that responsibility for a nuclear explosion, if any, should be ascribed to the Republic of South Africa.[6][7] Later, the Administration of President Carter asked the Office of Science and Technology Policy (OSTP) to convene a panel of instrumentation experts to re-examine the Vela Hotel 6911 data, and to attempt to determine whether the optical flash detected came from a nuclear test.

Several U.S. Air Force WC-135B surveillance aircraft flew 25 sorties over that area of the Indian Ocean soon after the "double flash" was reported, but they failed to detect any sign of nuclear radiation.[8] However the WC-135 aircraft never entered the low-pressure air mass that had been over the suspicious area at the time of the light flashes.[3] Low levels of iodine-131 (a short-half-life product of nuclear fission) were reportedly detected in the thyroid glands of sheep in the Australian States of Victoria and Tasmania soon after the "detection" of the light flashes. Studies of wind patterns confirmed that fall-out from an explosion in the southern Indian Ocean could have been carried from there to southwestern Australia.[9]

The Arecibo ionospheric observatory and radio telescope in Puerto Rico detected an anomalous ionospheric wave during the morning of September 22, 1979, which moved from the southeast to the northwest, something that had been unobserved there before by the scientists.[10]

Office of Science and Technology Evaluation

An independent panel of scientific and engineering experts was commissioned by Frank Press, who was the Science Advisor to President Carter and the chairman of the OSTP, to evaluate the evidence and determine the likelihood that the event was a nuclear detonation. The chairman of this science panel itself was Dr. Jack Ruina of the Massachusetts Institute of Technology, and also the former director of the U.S. Department of Defense's Advanced Research Projects Agency. Reporting in the summer of 1980, the panel noted that there were some key differences in the detected optical signature from that of an actual nuclear explosion, particularly in the ratio of intensities measured by the two detectors on the satellite. Also, although the brightness of the flash was explainable only if the flash had occurred in a cloud-free area, the lack of any nuclear debris found by 25 Air Force WC-135 flights through the area could be explained if the detonation had occurred at a heavily-overcast site.

"Based on our experience in related scientific assessments," it was their collective judgment that the signal was spurious. The science panel's conclusion was that the signal "was probably not from a nuclear explosion, although we cannot rule out that this signal was of nuclear origin." The now-declassified report[1] contains details of the measurements made by the Vela Hotel satellite. The science panel was not able to reach a definitive conclusion on the origin of the "light flashes". The best analysis that they could do of the data suggested that, if the sensors were properly calibrated, any source of the "light flashes" was about 30 meters from the satellite (and hence it was a small event close up, not a big event far away). This was consistent with the hypothesis that a micrometeoroid had struck the satellite, ejecting a small cloud of dusty debris into space, and this had reflected sunlight into the sensors.

The fact that the explosion was picked up by only one of the two Vela satellites seems to support the science panel's assertion. The Vela satellites had previously detected 41 atmospheric tests - by countries such as France and the PRC - each of which was subsequently confirmed by other means, including testing for radioactive fallout. The absence of any such corroboration of a nuclear origin for the Vela Incident also suggests that the "double flash" signal was a spurious one.

Victor Gilinsky (former member of the Nuclear Regulatory Commission) attempted to cast doubt on the science panel's findings, arguing that its members were politically motivated.[11] There was some data that seemed to confirm that a nuclear explosion was the source for the "double flash" signal. There the "anomalous" traveling ionospheric disturbance that was measured at the Arecibo Observatory in Puerto Rico at the same time,[11] but that is many thousands of miles away in a different hemisphere of the Earth. A test in Western Australia conducted a few months later found some increased nuclear radiation levels.[12] However, a detailed study done by New Zealand's National Radiation Laboratory found no such evidence of excess radioactivity, and neither did a U.S. Government-funded nuclear laboratory.[13] Los Alamos National Laboratory scientists who worked on the Vela Hotel program have professed their conviction that the Vela Hotel satellite's detectors worked properly.[3][11]

Possible responsible parties

If a nuclear explosion did occur, it occurred within the 3000-mile-wide (4,800 km diameter) circle covering parts of the Indian Ocean, the South Atlantic, the southern tip of Africa, and a small part of Antarctica.[14]

South Africa

The Republic of South Africa did have a nuclear weapons program at the time, and it falls within that geographic location. Nevertheless, since the fall of apartheid, South Africa has disclosed most of the information on its nuclear weapons program, and according to international inspections and the ensuing International Atomic Energy Agency report, South Africa could not have constructed such a nuclear bomb until November 1979, two months after the "double flash" incident. Furthermore, the IAEA reported that all possible South African nuclear bombs had been accounted for. A Central Intelligence Agency (CIA) report dated January 21, 1980, that was produced for the United States Arms Control and Disarmament Agency concluded that:[15]

"In sum, State/INR finds the arguments that South Africa conducted a nuclear test on 22 September inconclusive, even though, if a nuclear explosion occurred on that date, South Africa is the most likely candidate for responsibility."

The United Nations Security Council Resolution 418 of 4 November 1977 introduced a mandatory arms embargo against South Africa, which also required all states to refrain from "any co-operation with South Africa in the manufacture and development of nuclear weapons".[16]


Well before the Vela Incident, American intelligence agencies had made the assessment that Israel probably possessed its own nuclear weapons.[17] In the 2008 book The Nuclear Express: A Political History of the Bomb and its Proliferation Thomas C. Reed and Danny B. Stillman stated their opinion that the "double flash" was the result of a joint South African-Israeli nuclear bomb test.[18] David Albright stated in his article about the "double flash" event in the Bulletin of Atomic Scientists that supposedly "most experts agree it was probably an Israeli test".[10]


India had carried out a nuclear test in 1974 (see Smiling Buddha). The possibility that India would test a weapon was considered, since it would be possible for the Indian Navy to operate in those waters so far south, but this was dismissed as impractical and unnecessary.[19]


Since the "double flash", if one existed, could have occurred not very far to the west of the French-owned Kerguelen Islands, it is possible that the French were testing a small neutron bomb[14] or other small tactical nuclear bomb.

Subsequent developments

Since 1980 some small amounts of new information have emerged. However, most questions remain unanswered:

  • In October 1984, a National Intelligence Estimate on the South African nuclear program noted:

    "There is still considerable disagreement within the Intelligence Community as to whether the flash in the South Atlantic detected by a US [...] satellite in September 1979 was a nuclear test, and if so, by South Africa. If the latter, the need for South Africa to test a device during the time frame of this Estimate is significantly diminished."[20]

    A shorter form of this wording was used in a subsequent National Intelligence Council memorandum of September, 1985.[21]
  • In February 1994, Commodore Dieter Gerhardt, a convicted Soviet spy and the commander of South Africa's Simon's Town naval base at the time, talked about the incident upon his release from prison. He said:

    "Although I was not directly involved in planning or carrying out the operation, I learned unofficially that the flash was produced by an Israeli-South African test, code-named Operation Phoenix. The explosion was clean and was not supposed to be detected. But they were not as smart as they thought, and the weather changed – so the Americans were able to pick it up."[22]

    Gerhardt further stated that no South African naval vessels had been involved, and that he had no first-hand knowledge of a nuclear test.
  • On April 20, 1997, the Israeli daily newspaper Haaretz quoted the South African Deputy Foreign Minister, Aziz Pahad, as confirming that the "double flash" from over the Indian Ocean was indeed from a South African nuclear test. Haaretz also cited past reports that Israel had purchased 550 tons of uranium from South Africa for its own nuclear plant in Dimona. In exchange, Israel supplied South Africa with nuclear weapons design information and nuclear materials to increase the power of nuclear warheads.[23] This statement was supposedly confirmed by the American Embassy in Pretoria, South Africa,[3][24] but Pahad's press secretary stated that Pahad had said only that "there was a strong rumor that a test had taken place, and that it should be investigated". In other words – he was merely repeating rumors that had been circulating for years.[25]
  • In October 1999, a white paper that was published by the U.S. Senate Republican Policy Committee in opposition to the Comprehensive Test Ban Treaty stated:

    "There remains uncertainty about whether the South Atlantic flash in September 1979 recorded by optical sensors on the U.S. Vela satellite was a nuclear detonation and, if so, to whom it belonged."[26]

  • In his 2006 book On the Brink, the retired C.I.A. clandestine service officer, Tyler Drumheller, wrote of his 1983–88 tour-of-duty in South Africa:

    "We had operational successes, most importantly regarding Pretoria's nuclear capability. My sources collectively provided incontrovertible evidence that the apartheid government had in fact tested a nuclear bomb in the South Atlantic in 1979, and that they had developed a delivery system with assistance from the Israelis."

Some related American information has recently been declassified in the form of heavily redacted reports and memoranda following applications made under the Freedom of Information Act. On May 5, 2006, many of these declassified documents were made available through the National Security Archive.

In popular culture

  • The Vela Incident formed the basis for a novel by Abe Ariel titled The Last War. The novel describes the test of an Israeli neutron bomb on an uncharted island.[27]
  • The Vela Incident was probably the inspiration for a Season 5 episode of The West Wing, "The Warfare of Genghis Khan".
  • The Vela Incident is the basis of a 2005 novel by Scott E. Douglas, Moby and Ahab on a Plutonium Sea: The Novel Which Ended the Cold War.[28]

See also


  1. ^ a b (Ad hoc Panel Report on the September 22 Event PDF of report released by FOIA request, Frank Ruina, chair, May 23, 1980.)
  2. ^ a b Jeffrey Richelson (May 5, 2006). "The Vela Incident: Nuclear Test or Meteoroid?". National Security Archive. Retrieved 2008-08-25.  
  3. ^ a b c d "Blast from the past: Los Alamos scientists receive vindication". Los Alamos National Laboratory. July 11, 1997. Retrieved 2009-06-25.  
  4. ^ " South Africa Stops Short Of Denying Nuclear Test, The Ledger, Lakeland, Florida, originally from The New York Times, 27 October 1979
  5. ^ Jeffrey T. Richelson, Spying on the Bomb: American Nuclear Intelligence from Nazi Germany to Iran and North Korea (W. W. Norton Co., 2006).
  6. ^ a b c NSC memo dated October 22, 1979 PDF file
  7. ^ a b NSC memo dated Jan. 7, 1980 PDF
  8. ^ "History of the Air Force Technical Applications Centre, Patrick Airforce Base, Florida: Volume 1" (PDF). United States Airforce via National Security Archive. 2006-05-04. Retrieved 2008-08-25.  
  9. ^ Frank Barnaby, The Invisible Bomb, I.B. Tauris & Co. Ltd., 1989, ISBN 1-85043-078-0.
  10. ^ a b David Albright (July/August 1994). The Flash in the Atlantic. The Bulletin of the Atomic Scientists. p. 42.,M1.  
  11. ^ a b c Victor Gilinsky (former Commissioner U.S. Nuclear Regulatory Commission) (May 13, 2004). "Israel's Bomb". The New York Review of Books. Retrieved 2007-12-08.  
  12. ^ Frank Barnaby. 1989. The Invisible Bomb, I.B. Tauris & Co. Ltd., ISBN 1-85043-078-0
  13. ^ Richelson, page 289
  14. ^ a b Richelson Op. Cit, page 296.
  15. ^ The 22 September 1979 Event, Interagency Intelligence Memorandum, National Security Archive, December 1979, pp. 11 (paragraph 41), MORI DocID: 1108245,, retrieved 2006-11-01  
  16. ^ UNSCR 418 of 4 November 1977: States should refrain from "any co-operation with South Africa in the manufacture and development of nuclear weapons"
  17. ^ Prospects for Further Proliferation of Nuclear Weapons, Special National Intelligence Estimate, CIA, 23 August 1974, SNIE 4-1-74,, retrieved 2008-01-20  
  18. ^ Hidden Travels of the Atomic Bomb Book Review New York Times December 8, 2008
  19. ^ Richelson Op. Cit, chapter seven, "The Double Flash".
  20. ^ Trends in South Africa's Nuclear Security Policies and Programs
  21. ^ The Dynamics of Nuclear Proliferation: Balance of Incentives and Constraints
  22. ^ David Albright, 'South Africa and the affordable bomb', Bulletin of the Atomic Scientists, July/August 1994.
  23. ^ Associated Press, archived at
  24. ^
  25. ^ Albuquerque Journal, 11 July, archived at
  26. ^ Comprehensive Test Ban Treaty Cannot Be Verified
  27. ^ Ariel, Abe. The last war, Collins Australia, 1988, ISBN 0732224160, ISBN 9780732224165.
  28. ^ Moby and Ahab on a Plutonium Sea: The Novel Which Ended the Cold War, Publishamerica, 2005, ISBN 1413798411, ISBN 9781413798418


  • Aviation Week & Space Technology/July 21, 1997 page 33 "Admission of 1979 Nuclear Test Finally Validates Vela Data" by William B. Scott/Colorado Springs

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