Tag Archives: Thermonuclear Warhead

9 July 1962, 09:00:09 UTC, T + 13:41

Fireball of Operation Dominc Starfish Prime, 248 miles ( kilometers) above the Pacific Ocean, 9 July 1962.
Fireball of Operation Dominic-Fishbowl Starfish Prime, 248 miles (399.1 kilometers) above the Pacific Ocean, 9 July 1962.

9 July 1962: At 09:00:09 UTC, the United States detonated a thermonuclear warhead over the Pacific Ocean. This was part of the Operation Dominic-Fishbowl test series at Johnston Island, and was designated Starfish Prime.

At 08:46:28 UTC, a Douglas SM-75 Thor intermediate-range ballistic missile (IRBM) was launched from the Thor missile complex on Johnston Island, carrying a W-49 warhead in an AVCO Corporation Mk-2 reentry vehicle. The Mark 4/W-49 reached a peak altitude of 600 miles (965 kilometers) along a ballistic trajectory then began a descent.

Starfish Prime fireball was visible from Honolulu, Oahu. Hawaii.
Starfish Prime fireball was visible from Honolulu, Oahu, Hawaii, 898 miles (1,445.2 kilometers) from Ground Zero.

The W-49 detonated 36 kilometers (22 miles) southwest of Johnston Island at an altitude of 400 kilometers (246 miles) with an explosive yield of 1.45 megatons. The point of detonation deviated from the planned Air Zero by 1,890 feet (576 meters) to the north, 2,190 feet (668 meters) east, and +617 feet (188 meters) in altitude. The fireball was clearly visible in the Hawaiian Islands, more than 800 miles (1,288 kilometers) away.

The electromagnetic pulse (EMP) damaged electrical systems in The Islands, cutting power, damaging equipment and interrupting telephone systems. Brilliant auroras were visible, lasting about 7 minutes. Telstar, an American communications satellite that was placed in Earth orbit the following day, was also damaged by residual radiation from the detonation.

A Douglas SM-75/PGM-17A Thor IRBM. (U.S. Air Force)
A Douglas SM-75 Thor IRBM. (U.S. Air Force)

The Starfish Prime experiment was for the purpose of, “Evaluation of missile kill mechanisms produced by a high altitude nuclear detonation.” The electromagnetic effects on communications were also studied.

The Douglas Aircraft Company SM-75 Thor (redesignated PGM-17A in 1963) was a single-stage nuclear-armed ballistic missile, 65 feet (19.812 meters) long and 8 feet (2.438 meters) in diameter. It weighed 6,890 pounds (3,125.3 kilograms) empty and 110,000 pounds (49,895.2 kilograms) when fueled.

The SM-75 was powered by one Rocketdyne LR79-NA-9 rocket engine which produced 150,000 pounds of thrust. Two Rocketdyne LR101-NA vernier engines of 1,000 pounds thrust, each, provided directional control and thrust adjustments. The Thor was fueled with kerosene and liquid oxygen sufficient for 165 seconds of engine burn time.

The Thor could reach a maximum speed of 11,020 miles per hour (17,735 kilometers per hour) and had a maximum range of 1,500 miles (2,414 kilometers).

The W-49 thermonuclear warhead was designed by the Los Alamos Scientific Laboratory (LASL) and is believed to be a development of the earlier B-28 two-stage radiation-implosion bomb. It incorporated a 10-kiloton W-34 warhead as a gas-boosted fission primary, and had a one-point-safe safety system. The warhead had a diameter of 1 foot, 8 inches (0.508 meters) and length of  4 feet, 6.3 inches (1.379 meters). It weighed 1,665 pounds (755 kilograms).

The flash from the Starfish-Prime detonation, photographed from Maui in the Hawaiian Islands 15 seconds after detonation. (Los Alamos National Laboratory)
The flash from the Starfish-Prime detonation, photographed from Maui in the Hawaiian Islands, 15 seconds after detonation. (Los Alamos National Laboratory)

© 2018, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

7 March 1986

An LGM-118 Peacekeeper intercontinental ballistic missile begins to emerge from an underground silo at Vandenberg Air Force Base on the central coast of California. (U.S. Air Force)
LGM-118 Peacekeeper launch. (U.S. Air Force)
A LGM-118 Peacekeeper intercontinental ballistic missile leaving an underground silo at Vandenberg Air Force Base on the coast of California. (U.S. Air Force 021126-O-9999G-011)
The cold launch system ejects Peacekeeper from its canister with high-pressure steam. (U.S. Air Force photo)
Shock-absorbing tiles, which help the missile exit its canister, fall away as Peacekeeper is launched. (U.S. Air Force photo)
LGM-118 first stage solid-fuel rocket engine firing as shock absorbing tiles continue to fall away. (U.S. Air Force)

7 March 1986: An LGM-118 Peacekeeper intercontinental ballistic missile was launched from Vandenberg Air Force Base, California, with eight unarmed Mark 21 multiple independently targetable re-entry vehicles (MIRVs).

U.S. Air Force maintenance crews use a overhead crane and hoist to remove and install W87-0 warhead/Mk-21 Reentry Vehicles from the nose section of an LGM-118 Peacekeeper missile during training at Vandenberg AFB, California. (U.S. Air Force 000701-F-2828D-003)
LANDSAT 7 image of Kwajelein Atoll in the Marshall Islands, 12:29:01 UTC, 7 July 2014. (NASA)
Mark 21 MIRV warheads arrive at Kwajelein Atoll, 7 March 1986. (Department of Defense)

This photograph shows what it looked like on the receiving end at Kwajelein Atoll, 4,100 miles (6,598 kilometers) away.

Under START II, multiple warhead missiles were deactivated. The last of the LGM-118 Peacekeeper was removed from service by 2005. Some of the boosters have been used for satellite launch vehicles.

© 2018, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather