HARDTACK-Teak was an exoatmospheric high altitude nuclear weapon test performed during Operation Newsreel. It was launched from Johnston Atoll on a Redstone missile. On 1 August 1958, the 3.88 MtonTNT shot detonated at an altitude of 76.8 km. Along with HARDTACK-Orange it was one of the two largest high-altitude nuclear explosions.

Planning

The 3.8-megaton detonation was planned to occur at an altitude of 250000 ft above a point approximately 6 mi south of Johnston Island. However, due to a programming failure, it burst directly above the island at the desired altitude, making the island the effective ground zero. This brought the explosion 2000 ft nearer the launch site control and analysis crews than intended. The Teak test was originally planned to be launched from Bikini Atoll, but Lewis Strauss, chairman of the United States Atomic Energy Commission opposed the test because of fears that the flash from the nighttime detonation might blind Islanders who were living on nearby atolls. He finally agreed to approve the high-altitude test on the condition that the launch point be moved from Bikini Atoll to the more remote site at Johnston Island. According to the United States Defense Nuclear Agency report (DNA6038F) on Operation Hardtack I: "Johnston Island was well situated for the high-altitude tests because of its isolation, the nearest inhabited island being 538 mi away. On the other hand, operations there had to consider aircraft and ship routes from Hawaii to Asia, as well as the close-in hazards of missile launch in a confined area and the firing of missiles over water areas used for ship anchorage. That the hazard of primary concern is flashblindness and/or retinal burn expected to result from the programmed detonation. This hazard is calculated to extend to a range of 435 statute miles [435 mi] at the surface..."

Effects

When the warhead burst at 76.8 km directly above Johnston Island, the flash effectively turned night into day, as shown in the "After" photo in the section above. The initial glow faded over a period of about 30 seconds. The thermal radiation output of the explosion was such that observers were forced to take cover in the "shade" for the first few moments, as can be seen in film footage of the test. Teak caused communications impairment over a widespread area in the Pacific basin. This was due to the injection of a large quantity of fission debris into the ionosphere. The debris prevented normal ionospheric reflection of high-frequency (HF) radio waves back towards Earth, which disrupted most long-distance HF radio communications. The nuclear detonation occurred at 10:50 UTC on 1 August 1958 (which was 11:50 p.m., Johnston Island local time, on 31 July 1958). According to the book Defense's Nuclear Agency 1947–1997, when the Teak detonation occurred: According to page 269 of the Defense Nuclear Agency report on Operation Hardtack: According to civilian observer reports contained in the official United States Defense Nuclear Agency report on Operation Hardtack I: