This Week In History: The mysterious ‘double flash’

In 1979, a US nuclear detonation satellite detected a flash of light that appeared to be a nuclear blast.

Vela satellite 370 (photo credit: Wikimedia Commons)
Vela satellite 370
(photo credit: Wikimedia Commons)
On September 22, 1979, at 00:53 GMT a US nuclear detonation satellite detected a mysterious "double flash" of light in the southern oceans, characteristic of a nuclear explosion. It was unclear at the time whether the flash came from the South Atlantic or the Indian Ocean, but hydroacoustic data later located it to be in the latter, in the vicinity of South Africa's Prince Edward Island. The event fueled unconcluded speculation over whether the event was a nuclear test, and if so who was responsible for it. The dominant theory posits that it was a joint Israeli-South African test.The double flash is characteristic of an atmospheric nuclear explosion. However, certain elements identified by the Vela 6911 satellite left room for doubt over the nature of the flash. A discrepancy that heavily contributed to this doubt concerned the two readings of the bhangmeters, humorously named after Indian cannabis to reflect skepticism on the part of one of the devices' engineers concerning its effectiveness. The device is installed on satellites to detect atmospheric nuclear detonation, and in the case of the South Pacific flash, the pair of sensors did not agree on the flashes brightness. In fact, the system proved to be highly effective and prior to September 1979, when the orbital surveillance system had successfully recorded 41 atomic detonations, 12 of which were spotted by satellite Vela 6911.Since the satellite had been operating for 10 years, three years longer than its expected lifespan, and its electromagnetic pulse (EMP) sensor was inoperative, the reliability of the detection was brought to question. The US air-force planes flew through the skies near the blast 25 times following the blast, but failed to detect any radiation. However, the Arecibo Observatory in Puerto Rico detected a strange ionospheric wave moments after the Vela explosion and a burst of auroral light flashed over the Antarctic base around the same time, supporting belief that it was a nuclear explosion.Shortly after news of the explosion had reached ears of then-US president Jimmy Carter, the US Administration appointed The Ruina Panel, comprising a selection of scientists and headed by Professor of electrical engineering Jack P.Runia, to review the Vela data. The detection was an unwelcome intrusion in the pre-election period, as Carter - who had placed great emphasis on nuclear non-proliferation - would be expected to take action if a nuclear test was confirmed, and fingers were pointed at its ally Israel and/or South Africa as suspected culprits behind the incident.The Ruina Panel found, at the end of September 1979, that the double flash was possibly not a nuclear test, and in May 1980, concluded that it was more likely an artifact of a meteoroid hitting the satellite and sunlight reflecting off the particles ejected as a result of the collision.  However, the panel, stated, "we cannot rule out that this signal was of nuclear origin."In response to the Carter Administration panel, scientists at the Los Alamos National Laboratory (LANL) in New Mexico launched their own investigation, producing the following statement by David Albright, President of the Institute for Science and International Security: "This document provides support for those who conclude that a nuclear explosion occurred south of South Africa in September 1979. It also confirms the importance of declassifying more information about this possible nuclear test."Israel was believed to be in possession of nuclear weapons but has a shortage of land for testing purposes, therefore it could have benefited by cooperation with another country.  Meanwhile, while the location indicated South African involvement, a country that was known to be pursuing a weapons program. Former South African prime minister F.W. de Klerk disclosed in March 1993, that South Africa built nuclear weapons in the 1970s, and then voluntarily dismantled its nuclear arsenal and capacity according to international requirements. However, from documents made available to the IAEA, the nuclear watchdog does not believe that Pretoria's first nuclear bomb was ready until November 1979, two months after the Vela flash. Israel on its part, has never admitted to having a nuclear weapons program, and maintains a policy of deliberate ambiguity. Both Israel and South Africa vehemently denied having carried out a nuclear test, or any nuclear cooperation between the two countries whatsoever.The South African prime minister categorically stated that the country had not received any foreign help in developing the nuclear devices and said that it: "never carried out a nuclear test, not in the atmosphere nor underground. Nor was South Africa involved in any other country's nuclear test."In 1994, the issue was again brought to the forefront of discussion, when convicted Soviet spy Commodore Dieter Gerhardt, who at the time of the "double flash" was the commander of the Simonstown naval base near Cape Town, told City Press that the flash was the product of an Israel-South African test code-named "Operation Phenix."  Those who believe that a nuclear test and been conducted, believe Simonstown was the point of departure for the navy vessels. "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," City Press quoted Gerhardt as saying. He said that he had obtained this information unofficially, and was not directly involved in the operation.Three years later, former South African Deputy Foreign Minister Aziz Pahad told Haaretz that the flash was "definitely a nuclear test." He further confirmed that "the nuclear issue was secret, and that many documents were destroyed although not all of them. There are many reports of relations between the two states' scientists and cooperation regarding very specific equipment."  Aziz, however, later said that his remarks had been taken out of context and he had only said that "there was a strong rumor that a test had taken place, and that it should be investigated."Belief that the Vela explosion was a joint Israeli-South African nuclear test is part of wider speculation of nuclear cooperation between the two countries, which reached a climax in 2010, when The Guardian caused a storm with its "exclusive" report, claiming that Israel offered to sell nuclear weapons to apartheid South Africa in 1975. The story alleged that in 1975, then- South African defense minister PW Botha met secretly with Shimon Peres, Israel's defense minister at the time, in which Botha requested the weapons and Peres offered three warhead versions for sale. The Guardian report claims that it contains “The first documentary evidence” of Israel’s possession of nuclear weapons. The British daily alleged that the documents confirmed accounts by Gerhardt, who said that Israel offered eight Jericho ballistic missiles armed with “special warheads” to South Africa.  Peres' office denied the allegations, expressing "regret that the newspaper did not find it right to ask for an official response and examine the facts with official Israeli sources." Additional sources added that "there is no doubt these papers that allegedly document a nuclear missiles sales deal are completely fabricated."To this day, Israel is believed to be the only nuclear-armed state in the Middle East, but it has neither confirmed nor denied this, ambiguously stating that "Israel will not be the first nation to introduce nuclear weapons to the Middle East." In 2001 it responded to a Non-Profileration Treaty resolution calling for Israel's membership, saying  that "it ignores the realities of the Middle East and the real threats facing the region and the entire world." The Washington Post's Patrick B. Pexton recently quoted the spokesman for the Israeli Embassy in Washington Aaron Sagui as reiterating Israel's stance and saying "Israel supports a Middle East free of all weapons of mass destruction following the attainment of peace.” Thus while the uphill battle for Middle East peace continues and the Iranian nuclear threat still stands, it seems that the Jewish state will do all it can to keep its alleged nuclear program shrouded in mystery.