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 near the Prince Edward Islands or Antarctica. There is uncertainty as to the true nature of the flash though it is widely believed to have been the result of a nuclear detonation.
While a "double flash" signal is characteristic of a nuclear weapons test, the signal might have been a spurious electronic signal that was generated by an aging detector in an old satellite or a meteoroid hitting the Vela satellite. No corroboration of an explosion, such as the presence of nuclear byproducts in the air, was ever publicly acknowledged, even though there were numerous passes in the area by U.S. Air Force planes that were specifically designed to detect airborne radioactive dust. Other examiners of the data, including the Defense Intelligence Agency (DIA), the U.S. Naval Research Laboratory (NRL), and defense contractors, have come to the conclusion that the flash was a result of a nuclear detonation. Much of the information relating to the event remains classified.
The most widespread theory among those who believe that the flash was of nuclear origins was that it resulted from a joint South African and Israeli nuclear test. The topic remains highly disputed today.
The "double flash" was detected on September 22, 1979, at 00:53 GMT, by the American Vela satellite 6911, which carried various sensors that had been designed specifically to detect nuclear explosions that contravened the Partial Nuclear Test Ban Treaty. 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 an atmospheric nuclear explosion: the initial brief, intense flash, followed by the second longer flash.
The satellite reported the characteristic double flash of a small atmospheric nuclear explosion of two to three kilotons, in the Indian Ocean between The Crozet Islands (a very small, sparsely inhabited French possession) and the Prince Edward Islands which belong to South Africa at Coordinates: . The previous 41 double flashes that the Vela satellites detected were all subsequently confirmed to be nuclear explosions.
There was, and remains, much doubt[page needed] 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.
Additionally, 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 extraterrestrial object strike, such as an asteroid, occurring. The Vela satellite's flash detectors were sensitive to lightning superbolts,[page needed] which resulted in two scientists, John Warren and Robert Freyman from the Los Alamos National Laboratory (then called the Los Alamos Scientific Laboratory), immediately flying to and investigating a rare, overland superbolt occurrence on Bell Island, Newfoundland, in April 1978. Their observations of the event, called the 'Bell Island Boom', noted building structural damage, dead farm animals and destroyed electrical devices amongst other evidence (the superbolt's blast was heard 55 kilometers away in Cape Broyle, Newfoundland).[a] The Bell Island Boom was among some 600 "mystery booms" that occurred along the North American eastern seaboard from late 1977 to mid‑1978.
Nonetheless, the initial assessment by the United States National Security Council (NSC), with technical support by the Naval Research Laboratory[page needed] in October 1979 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."[page needed] A later NSC report revised this position to "a position of agnosticism" about whether a test had occurred or not.[page needed] The NSC concluded that responsibility for a nuclear explosion, if any, should be ascribed to the Republic of South Africa.[page needed][page needed]
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. 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. It was reported that low levels of iodine-131 (a short-half-life product of nuclear fission) were detected in sheep in the southeastern Australian States of Victoria and Tasmania soon after the event. Sheep in New Zealand showed no such trace.
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, an event which had not been observed previously by the scientists.
The administration of USA 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. The outcome was important to Carter, as his presidency and 1980 re-election campaign prominently featured the themes of nuclear nonproliferation and disarmament. In particular, the SALT II treaty had been signed three months earlier, and was pending ratification by the United States Senate.
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. The now-declassified report contains details of the measurements made by the Vela Hotel satellite.
The explosion was picked up by a pair of sensors on only one of the several Vela satellites; other similar satellites were looking at different parts of the earth, or weather conditions precluded them seeing the same event. 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 suggested that the "double flash" signal was a spurious 'zoo' signal of unknown origin, possibly caused by the impact of a micrometeoroid. Such 'zoo' signals which mimicked nuclear explosions had been received several times earlier.
Their report noted that the flash data contained "many of the features of signals from previously observed nuclear explosions", but that "careful examination reveals a significant deviation in the light signature of the September 22 event that throws doubt on the interpretation as a nuclear event". The best analysis that they could offer of the data suggested that, if the sensors were properly calibrated, any source of the "light flashes" were spurious "zoo events". Thus their final determination was that while they could not rule out that this signal was of nuclear origin, "based on our experience in related scientific assessments, it is our collective judgment that the September 22 signal was probably not from a nuclear explosion".
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. There was some data that seemed to confirm that a nuclear explosion was the source for the "double flash" signal. There was the "anomalous" traveling ionospheric disturbance that was measured at the Arecibo Observatory in Puerto Rico at the same time, but 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.[page needed] 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. 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.
Leonard Weiss, at the time Staff Director of the Senate Subcommittee on Energy and Nuclear Proliferation, has also raised concerns about the findings of the Ad-Hoc Panel, arguing that it was set up by the Carter administration to counter embarrassing and growing opinion that it was an Israeli nuclear test. Specific intelligence about the Israeli nuclear program was not shared with the panel whose report therefore produced the plausible deniability that the administration sought.
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.
In 1979, the DIA reported that the test may have been a Soviet test done in violation of the 1963 Partial Nuclear Test Ban Treaty. The USSR had conducted a few secret underwater tests in the Pacific in 1959.
Well before the Vela Incident, American intelligence agencies had made the assessment that Israel probably possessed its own nuclear weapons. According to journalist Seymour Hersh, the detection was the third joint Israeli-South African nuclear test in the Indian Ocean, and the Israelis had sent two IDF ships and "a contingent of Israeli military men and nuclear experts" for the test. Author Richard Rhodes also concludes the incident was an Israeli nuclear test, conducted in cooperation with South Africa, and that the United States administration deliberately obscured this fact in order to avoid complicating relations with South Africa. Likewise, Leonard Weiss offers a number of arguments to support the test being Israeli, and claims that successive US administrations continue to cover up the test to divert unwanted attention that may portray its foreign policy in a bad light. 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. David Albright stated in his article about the "double flash" event in the Bulletin of Atomic Scientists that "If the 1979 flash was caused by a test, most experts agree it was probably an Israeli test".
The Republic of South Africa did have a nuclear weapons program at the time, and it falls within that geographic location. Nevertheless, it had acceded to the Partial Test Ban Treaty in 1963, and 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:
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 November 4, 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".
India had carried out a nuclear test in 1974 (codenamed 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, however, this was dismissed as impractical and unnecessary (given the fact that India had signed and ratified the Limited Test Ban Treaty or LTBT in 1963, and had complied with it even in its first test).
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 or other small tactical nuclear bomb.
Since 1980, some small amounts of new information have emerged. However, most questions remain unanswered:
TIROS-N plasma data and related geophysical data measured on 22 September 1979 were analyzed to determine whether the electron precipitation event detected by TIROS-N at 00:54:49 universal time could have been related to a surface nuclear burst (SNB). The occurrence of such a burst was inferred from light signals detected by two Vela bhangmeters −2 min before the TIROS-N event. We found the precipitation to be unusually large but not unique. It probably resulted from passage of TIROS-N through the precipitating electrons above a pre-existing auroral arc that may have brightened to an unusually high intensity from natural causes −3 min before the Vela signals....We conclude that such an event, although rare, is not unique and, furthermore, that this particular event was associated with an auroral arc that probably existed before the Vela event. Although it may be argued that the segment of the arc sampled by the TIROS-N was intensified by a SNB, we find no evidence to support this thesis or to suggest that the observation was anything but the result of natural magnetospheric processes.
A shorter form of this wording was used in a subsequent National Intelligence Council memorandum of September, 1985.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.[page needed]
Gerhardt further stated that no South African naval vessels had been involved, and that he had no first-hand knowledge of a nuclear test.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.
The U.S. government should declassify additional information about the event. A thorough public airing of the existing information could resolve the controversy.
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.
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