Page:Operation Crossroads 1946.pdf/88

 CHAPTER 4

TEST OPERATIONS

CROSSROADS was primarily a sea-based operation. The islands of Bikini Atoll were used as sites for instrument locations and as recreation areas. However, a Navy Construction Battalion had quarters for its men on Bikini Island. Joint Task Force 1 (JTF 1) personnel lived at Kwajalein, Enewetak, and aboard ships in Bikini Lagoon. They commuted to their work sites in the target array or at island-based measurement sites.

In Test ABLE, the weapon was dropped from an Army Air Forces B-29 (nicknamed "Dave's Dream") based at Kwajalein. The bomb burst in the air 520 feet (158 meters) over the target ships. In the BAKER test the weapon was suspended in a waterproof container 90 feet (27 meters) below LSM-50, anchored at the center of the target fleet. A third test, to have been called CHARLIE, would have been a deep underwater test, but it was cancelled after Test BAKER.

The target fleet was unmanned for both tests and was anchored in the northeastern area of Bikini Lagoon off Bikini Island. For ABLE 22 landing craft and for BAKER 24 landing craft were beached on the lagoon side of this island, simulating boats in an amphibious operation. Military equipment (including airplanes), animals, and scientific instruments were aboard the target ships. Two anchored seaplanes were also part of the target fleet.

The manned JTF 1 support ships withdrew from the lagoon before the tests and remained east of the atoll or were at other atolls until it was safe to reenter the lagoon. Nontarget small craft were moored (unmanned) in the lagoon off Eneu Island about 5 nmi (9.3 km) south of the test area. Among these were several drone boats equipped to be remotely controlled. After each detonation the drones were guided by aircraft and USS Begor (APD-127) to areas in the target array to collect water samples and take radiation readings. After the water samples were collected, the drones were guided back to Begor where they were hosed down to remove radioactive contamination (Figure 20) and the samples removed. After each test the drones were followed by six patrol motor gunboats (PGMs) and twenty landing craft (LCPLs) with radiation monitors aboard. Radiation intensity measurements were sent by radio to the Radsafe Control Center. From this information and that gathered from aircraft equipped with radiation detectors, it was determined when a safe recovery to the lagoon by the main body of the fleet could be made.

PRE-TEST OPERATIONS

Preparation for the tests began in January 1946 when the atoll was surveyed by USS Allen M. Sumner (DD-692) and USS Bowditch (AGS-4). The survey was finished in April.

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