News and opinions from Glenn Elert

A double flash characteristic of a nuclear explosion was recorded by the US Department of Defense Vela 6911 satellite in the South Indian Ocean on this day in 1979. No government has officially taken credit for the event, but it is generally thought to have been a joint Israeli-South African test of a low-yield fission bomb.

Further Reading (listed in reverse chronological order, just like a resume):

• The Vela Incident, Paul Drye, Passing Strangeness (7 February 2009).
• The Vela Incident, Alan Bellows, Damn Interesting (16 October 2007).
• The Vela Incident: Nuclear Test or Meteoroid? National Security Archive Electronic Briefing Book No. 190 (5 May 2006). This web page comes with a great list of original, declassified source material.
• Nuclear Weapons Testing: Israel, GlobalSecurity.org (28 April 2005)
• Report on the 1979 Vela Incident, Carey Sublette, The Nuclear Weapon Archive (1 September 2001).
• Proliferation: A flash from the past, David Albright and Corey Gay, Bulletin of the Atomic Scientists, vol. 53, no. 06 (November/December 1997): 15-17.
• South Africa and the affordable bomb, David Albright, Bulletin of the Atomic Scientists, vol. 50, no. 04 (July/August 1994): 37-47.

Do your own independent research. Search for the phrase "South Africa" and the keyword "Nuclear" at the Central Intelligence Agency’s Freedom of Information Act Electronic Reading Room. It’s not easy to use, but there are a lot of interesting, original documents to peruse in this online archive. Also great for people who don’t like reading a lot since the CIA has a thing for censoring text. [As

Leo Szilard crosses the street on his way from the Imperial Hotel to the British Museum.

I was walking the streets of London, and I remember that I stopped for a red light at the intersection of Southampton Row. As the light changed to green and I crossed the street, it suddenly occurred to me that if we could find an element which is split by neutrons and emit two neutrons when it absorbed one neutron, such an element, if assembled in sufficiently large mass, could sustain a nuclear chain reaction.

Leo Szilard was a physicist born in Hungary in 1989. At the end of the First World War in 1918, he would have been 20 years old. This was not a good time for anyone living in Hungary as Soviet style communism was gaining hold. Ambitious young people were quick to leave. Szilard moved to Germany and worked alongside many of the great names in physics at the time: Albert Einstein and Max Planck to name two.

In 1933 when Adolph Hitler became Chancellor of Germany, the Jewish Szilard decided it was time to move again — this time to London. It was that year when he became the first person to conceive of a nuclear chain reaction. Szilard wrote about this time in his 1968 memoir.

In 1932 while I was still in Berlin, I read a book by H.G. Wells. It was called The World Set Free. This book was written in 1913, one year before the [First] World War, and in it H.G. Wells describes the discovery of artificial radioactivity and puts it in the year of 1933, the year in which it actually occurred. He then proceeds to describe the liberation of atomic energy on a large scale for industrial purposes, the development of atomic bombs, and a world war which was apparently fought by allies of England, France, and perhaps including America, against Germany and Austria, the powers located in the central part of Europe. He places this war in the year 1956, and in this war the major cities of the world are all destroyed by atomic bombs.

Szilard then went on to recall a conversation he had with H.G. Wells’ German distributor. The discussion made him consider moving into nuclear physics. The memoir jumps ahead to London.

I was not thinking any more about this conversation or about H.G. Wells’s book either, until I found myself in London about the time of the British Association meeting in September 1933. I read in the newspapers a speech by Lord Rutherford, who was quoted as saying that he who talks about the liberation of atomic energy on an industrial scale is talking moonshine. This set me pondering as I was walking the streets of London, and I remember that I stopped for a red light at the intersection of Southampton Row. As the light changed to green and I crossed the street, it suddenly occurred to me that if we could find an element which is split by neutrons and which would emit two neutrons when it absorbed one neutron, such an element, if assembled in sufficiently large mass, could sustain a nuclear chain reaction.

Szilard refined the notion of a chain reaction and in 1934 he filed the first patents for a nuclear reactor — one that described the generation of radioactive elements by neutron bombardment (a production reactor) and a second that described a nuclear chain reaction, in which more than one neutron is emitted per neutron absorbed (the essential idea behind a bomb). The second patent was assigned to the British Admiralty and declared secret. Szilard credited Wells with this decision.

It was the first time, I think, that the concept of critical mass was developed and that a chain reaction was seriously discussed. Knowing what this would mean — and I knew it because I had read H.G. Wells — I did not want this patent to become public.

The details of Szilard’s method proved to be unworkable, but the underlying idea was sound. In 1942, he teamed up with Enrico Fermi at the University of Chicago and built the world’s first successful controlled nuclear chain reaction. Code named Chicago Pile 1, it was hidden under the stands of an athletic field. The site is now dormitories, but a memorial with an abstract bronze statue marks the spot . Work on the project was so secret that Fermi’s wife did not learn of it until 1945. Fermi and Szilard filed a patent in 1944 on their new design and again asked that it be declared a state secret. It was not released until 1955.

The first beam in the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) was successfully steered around the full 27 kilometres of the world’s most powerful particle accelerator at 10:28 in the morning on 10 September 2008. The LHC is a device for understanding the fundamental laws of nature through experimentation.

Source: CERN

Date: 29 August 1949
Code name: RDS-1 (РДС-1), Reaktivniy dvigatel’ Stalina (Реактивный Двигатель Сталина), "Stalin’s Jet Engine"
Type: plutonium fission
Yield: 10–20 thousand tons of TNT
Location: Semipalatinsk, Kazakhstan

The Soviet Union exploded its first nuclear weapon near Semipalatinsk, Kazakhstan on this day in 1949. It was a plutonium fission device similar in design and yield to the test device detonated near Alamogordo, New Mexico and the aerial bomb dropped on Nagasaki, Japan in the summer of 1945. The Soviet code name for the device was “Stalin’s Jet Engine” (Реактивный Двигатель Сталина).