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High-altitude nuclear explosion

High-altitude nuclear explosions are the result of nuclear weapons testing. Several such tests were performed at high altitudes by the United States and the Soviet Union between 1958 and 1962.

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EMP generationEdit

The strong electromagnetic pulse (EMP) that results has several components. In the first few tens of nanoseconds, about a tenth of a percent of the weapon yield appears as powerful gamma rays with energies of one to three mega-electron volts (MeV, a unit of energy). The gamma rays penetrate the atmosphere and collide with air molecules, depositing their energy to produce huge quantities of positive ions and recoil electrons (also known as Compton electrons). The impacts create MeV-energy Compton electrons that then accelerate and spiral along the Earth's magnetic field lines. The resulting transient electric fields and currents that arise generate electromagnetic emissions in the radio frequency range of 15 to 250 megahertz (MHz, or fifteen million to 250 million cycles per second). This high-altitude EMP occurs between 30 and 50 kilometers (18 and 31 miles) above the Earth's surface. The potential as an anti-satellite weapon became apparent in August 1958 during Hardtack Teak. The EMP observed at the Apia Observatory at Samoa was four times more powerful than any created by solar storms, while in July 1962 the Starfish Prime test, damaged electronics in Honolulu and New Zealand (approximately 1,300 kilometers 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. The radius for an effective satellite kill for the various Compton radiation 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 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.

DrawbacksEdit

There are 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 indiscriminate damage to other satellites, including one's own satellites. Starfish Prime produced an artificial radiation belt in space that soon destroyed three satellites (Ariel, TRAAC, and Transit 4B all failed after traversing the radiation belt, while Cosmos V, Injun I and Telstar 1 suffered minor degradation, due to some radiation damage to solar cells, etc.). 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, which caused NASA concern with regard to its manned space exploration programs.

Differences from atmospheric testsEdit

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,' reminiscent of other space-based explosions 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 documentary maker Peter Kuran 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 50 kilometers (31 mi), 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.

Soviet high-altitude testsEdit

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 saber rattling.

The worst effects of a Soviet high-altitude test occurred on 22 October 1962, in the Soviet Project K nuclear tests (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 Tselinograd and Alma-Ata.

The Partial Test Ban Treaty was passed the following year, ending atmospheric and exoatmospheric nuclear tests. The Outer Space Treaty of 1967 banned the stationing and use of nuclear weapons in space. The Comprehensive Nuclear-Test-Ban Treaty of 1996 prohibits all kinds of nuclear explosions; whether over- or underground, underwater or in the atmosphere.

List of high-altitude nuclear explosionsEdit

 
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.
Mission Date Yield Altitude
  USA Hardtack IJohnston Atoll, Pacific Ocean
Yucca 28 April 1958 1.7 kt 26.2 km
Teak 1 August 1958 3.8 kt 76.8 km
Orange 12 August 1958 3.8 Mt 34 km
  USA Argus – South Atlantic Ocean
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
  Soviet Union – 1961 tests – Kapustin Yar
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
  USADominic I – (Operation Fishbowl) – Johnston Atoll, Pacific Ocean
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
  Soviet UnionProject K – Kapustin Yar
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 alsoEdit

ReferencesEdit

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