Tightrope flies from Johnston Island, and Operation Fishbowl is finished
More than three months after a Bluegill Prime missile blew up on its Johnston Island pad, the United States finished what it had started in the Pacific. On November 4, 1962, a low-yield device named Tightrope rose on an XM-33 Strypi rocket, the final shot of Operation Fishbowl. It was also the last atmospheric nuclear test the United States conducted. The 1963 Partial Nuclear Test Ban Treaty then left the United States only underground tests.
Tightrope closed the era of American nuclear tests in the open sky. The 1963 Partial Nuclear Test Ban Treaty barred tests in the atmosphere, underwater and in space. American testing went underground. What Fishbowl taught about electromagnetic pulse and radiation belts informed military planning and satellite protection.
QWhich satellites did Starfish Prime cripple, and how long did the last one hold out?
The artificial radiation belts created by Starfish Prime on July 9, 1962, damaged or failed several satellites: Traac, Transit 4B, Injun I, Telstar I and Ariel. The Soviet satellite Kosmos 5 was on the list too. Telstar I lasted longest. It did not fail completely until February 21, 1963, a little over three months after Tightrope flew from Johnston Island. The radiation made no distinction between American, British and Soviet hardware, and the damage to the new communications satellite showed anyone launching spacecraft that events above the Pacific mattered to them.
QHow far from the blast did Starfish Prime start shutting off the lights?
About 1,445 kilometers, or 900 miles. That was the distance from the Starfish Prime detonation to Hawaii, where the electromagnetic pulse damaged electrical systems. Streetlights went out, burglar alarms went off, and a telephone company microwave link was damaged. Electromagnetic pulse was one of the very questions Fishbowl had been designed to answer, and the planners had listed it alongside auroras, radiation belts and radio blackouts. Hawaii supplied a demonstration at a range few had expected. The shot took place about two weeks before the Bluegill Prime accident.
QWhy did auroras appear over Samoa, Fiji and Tonga after tests fired near Johnston Island?
Charged particles from the bursts followed the Earth's magnetic field. A Defense Department reference explains that for the tests near Johnston Island, particles entered the atmosphere in the northern hemisphere between Johnston Island and the main Hawaiian Islands, while the matching point at the other end of the magnetic field lines lay near the Samoan, Fiji and Tonga Islands. Auroras were observed in those areas as well as near the explosions. During Checkmate, observers at Samoa saw a white flash that faded to orange and vanished in about a minute. The sky 2,000 miles from the launch site was part of the experiment.
