High altitude nuclear explosion

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Bluegill Triple Prime shot, 1962, altitude 31 miles

How the peak EMP on the ground varies with the weapon yield and burst altitude. Note that the yield here is the prompt gamma ray output measured in kilotons. This varies from 0.1-0.5% of the total weapon yield, depending on weapon design. The 1.4 Mt total yield 1962 Starfish test had an output of 0.1%, hence 1.4 kt of prompt gamma rays. (The blue 'pre-ionisation' curve applies where gamma and x-rays from the weapon's primary stage ionise the atmosphere, making it electrically conductive before the main pulse from the thermonuclear stage. The pre-ionisation can literally short out part of the final EMP.)

The mechanism for a 400 km high altitude burst EMP: gamma rays hit the atmosphere between 20-40 km altitude, ejecting electrons which are then deflected sideways by the earth's magnetic field.

High altitude nuclear explosions have historically been nuclear explosions which take place outside the Earth's atmosphere. Such explosions have been tests of nuclear weapons, used to determine the effects of the blast and radiation in the environment.

The only nations to detonate nuclear weapons in outer space are the United States and the Soviet Union. The U.S. program began in 1958, with the Teak and Orange shots, both 3.8 megatons. These warheads were initially carried on Redstone rockets. Later tests were delivered by Thor missiles for Operation Dominic I tests, and modified Lockheed X-17 missiles for the Argus tests. The purpose of the shots was to determine both feasibility of nuclear weapons as an anti-ballistic missile defense, as well as a means to defeat satellites and manned orbiting vehicles in space.

As it was realized that nuclear weapons created an electromagnetic pulse, the potential as an anti-satellite weapon became apparent: in August 1958 during Hardtack Teak, the EMP was observed at the Apia Observatory at Samoa to be four times more powerful than any created by solar storms, while in July 1962 the Starfish Prime test damaged electronics in Honolulu (approximately 800 miles away), fused 300 street lights on Oahu (Hawaii), set off about 100 burglar alarms, and caused the failure of a microwave repeating station on Kauai, which cut off the sturdy telephone system from the other Hawaiian islands [link]. The radius for an effective satellite kill for the various prompt radiations produced by such a nuclear weapon in space was determined to be roughly 80 km. Further testing to this end was carried out, and embodied in a Department of Defense program, Program 437.

The problems with nuclear weapons carried over to testing and deployment scenarios, however. Because of the very large radius associated with nuclear events, it was nearly impossible to prevent indescriminate damage to other satellites, including one's own satellites. Starfish Prime produced an artificial radiation belt in space which soon destroyed three satellites (Ariel, Traac, and Transit 4B all failed after transversing the radiation belt, while Cosmos V, Injun I and Telstar suffered minor degradation, due to some radiation damage to solar cells, etc. [link]). The radiation dose rate was at least 60 rads/day at four months after Starfish for a well-shielded satellite or manned capsule in a polar circular earth orbit [link], which caused NASA concern with regard to its manned space exploration programs.

In general, nuclear effects in space (or very high altitudes) have a qualitatively different display. While an atmospheric nuclear explosion has a characteristic mushroom-shaped cloud, high-altitude and space explosions tend to manifest a spherical 'cloud,' until distorted by earth's magnetic field, and the charged particles resulting from the blast can cross hemispheres to create an auroral display which has led one filmmaker to characterize these detonations as 'the rainbow bombs'. The visual effects of a high-altitude or space-based explosion may last longer than atmospheric tests, sometimes in excess of 30 minutes. Heat from the Bluegill Triple Prime shot, at an altitude of 31 miles, was felt by personnel on the ground at Johnston Atoll, and this test caused retina burns to two personnel at ground zero who were not wearing their safety goggles [link].

How the area is affected depends on the burst altitude.

The Soviets detonated four high-altitude tests in 1961 and three in 1962. During the Cuban Missile Crisis in October 1962, both the US and the USSR detonated several high-altitude nuclear explosions as a form of sabre-rattling. The Soviet tests were meant to demonstrate their anti-ballistic missile defenses which would supposedly protect their major cities in the event of a nuclear war. The worst effects of a Russian high altitude test occurred on 22 October 1962 (during the Cuban missile crisis), in ‘Operation K’ (ABM System A proof tests) when a 300-kt missile-warhead detonated near Dzhezkazgan at 290-km altitude. The EMP fused 570 km of overhead telephone line with a measured current of 2,500 A, started a fire that burned down the Karaganda power plant, and shut down 1,000-km of shallow-buried power cables between Aqmola and Almaty [link]. The Partial Test Ban Treaty was passed the following year, ending atmospheric and exoatmospheric nuclear tests.

List of high-altitude nuclear explosions

Hardtack-Orange shot, 43 km

The debris fireball and aurora created by the Starfish Prime test, as seen from a KC-135 aircraft at 3 minutes.

The Starfish Prime flash as seen through heavy cloud cover from Honolulu, 1,300 km away.

USA –  Hardtack I – Johnston Atoll, Pacific Ocean

• Yucca 28 April 1958, 1.7 kt, 26.2 km
• Teak, 1 August 1958, 3.8 Mt, 76.8 km
• Orange, 12 August 1958, 3.8 Mt, 43 km

• Argus I, 27 August 1958, 1.7 kt, 200 km
• Argus II, 30 August 1958, 1.7 kt, 240 km
• Argus III, 6 September 1958, 1.7 kt, 540 km

• Test #88, 6 September 1961, 10.5 kt, 22.7 km
• Test #115, 6 October 1961, 40 kt, 41.3 km
• Test #127, 27 October 1961, 1.2 kt, 150 km
• Test #128, 27 October 1961, 1.2. kt, 300 km

• Bluegill, 3 June 1962, failed
• Bluegill Prime, 25 July 1962, failed
• Bluegill Double Prime, 15 October 1962, failed
• Bluegill Triple Prime, 26 October 1962, 410 kt, 50 km
• Starfish, 20 June 1962, failed
• Starfish Prime, 9 July 1962, 1.4 Mt, 400 km
• Checkmate, 20 October 1962, 7 kt, 147 km
• Kingfish, 1 November, 1962, 410 kt, 97 km

• Test #184, 22 October 1962, 300 kt, 290 km
• Test #187, 28 October 1962, 300 kt, 150 km
• Test #195, 1 November 1962, 300 kt, 59 km

See also

• Outer Space Treaty

References

• Shooting down a star: the US Thor Program 437, nuclear ASAT, and copycat killers , Chun, Clayton K. S., 1999. ISBN 1-58566-071-X [link]
• Operation DOMINIC I, Defense Threat Reduction Agency Department of Public Affairs, February 2006. Viewed 9 February, 2006. [link]
• Operation Hardtack, United States Army, viewed 8 February, 2006 [link]
• High Altitude Nuclear Tests, Atomic Weapons Establishment (AWE) collection of thumbnail-sized colour photos of all American high altitude nuclear tests with captions, viewed 2 April 2006 [link]

External links

• ["High-altitude nuclear explosions"]
• [Peter Kuran's "Nukes in Space: The Rainbow Bombs"] – documentary film from 1999
• [United States high-altitude test experiences - A Review Emphasizing the Impact on the Environment]
• [Measured EMP waveform data and actual effects from high altitude nuclear weapons tests by America and Russia]
• [American and British official analyses of photography from high altitude nuclear explosions]

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