class="fn pginternal" href="@public@vhost@g@gutenberg@html@files@48038@[email protected]#fn_8" id="fr_8" tag="{http://www.w3.org/1999/xhtml}a">[8] devices. Its islands and reefs were burned by atomic heat, and the waters of its lagoon were contaminated by deposits of radioactive fallout. Thus, for almost a score of years, Bikini, a small outcropping of coral in the mid-Pacific, was identified with the earliest experiments in nuclear explosion.

Through the years of testing and later, Bikini also was the site of repeated biological investigations. Teams of scientists examined Bikini annually from 1946 to 1950 and from 1954 to 1958. Then in 1964, after an interlude of 6 years in which Bikini was undisturbed either by weapons tests or human visitors, scientists went there again to make a comprehensive ecological resurvey.

The scientists found in the Bikini ecosystem, in low but perceptible amounts, residual traces of radioactivity deposited by the tests. On certain islands, craters dug by nuclear explosions still gaped in the reefs. The test islands still bore nuclear scars, and in some areas of the lagoon corals and algae had been killed by silt stirred up by the detonations. But Bikini’s life system clearly was in a process of healing. Large islands were covered by regrowths of vegetation; on some, the masses of morning glory, beach magnolia and pandanus were growing so densely that field parties had extreme difficulty cutting paths through them. Bikini Atoll, scientists believed, needed only clearing and cultivation to make it once again suitable for human habitation.

Autoradiograph of a plankton sample collected from a Pacific lagoon a week after a 1952 test.

What, then, may be concluded from the Bikini case? A final answer still cannot be phrased. It is not a conclusion to say that nature and time have permitted recovery, reassuring though such knowledge may be. It becomes important to know the processes of recovery. Meantime, it is helpful to examine the Bikini case in the context of developments during the period from the end of World War II to the signing of the Nuclear Test Ban Treaty of 1963.

The Bikini Tests of 1946

The early period of nuclear testing in the atmosphere was a time that will not be seen again. It was the beginning of an era of unparalleled scientific activity and of worldwide emotional and intellectual adjustment to the knowledge that power of unimaginable magnitude, locked in the nucleus of the atom since the creation of the world, now could be released at will.

When World War II was ended, the impulse to test the new power was irresistible. There was profound curiosity about the revolutionary nature of the new force. There was a perplexed and fearful realization that the release of energy would have to be guarded and controlled. There was the knowledge that nuclear fission produced a miscellany of radioactive products presenting unexplored possibilities of hazard. The word “fallout” was coined to describe the deposition on the earth of radioactive debris from nuclear explosions.

Joint Task Force One

The first peacetime nuclear tests, conducted at Bikini in 1946 in a military-scientific exercise designated Operation Crossroads, were designed to assess the effects of nuclear weapons on naval vessels. The test organization, Joint Task Force One, an adaptation of the wartime joint task force combat concept, was a massive waterborne force including 42,000 members of the armed services, civilian scientists, consultants, and observers.

The Bikini Lagoon before testing.

Bikini Atoll was selected for the tests because, among other things, it was remote from heavily populated areas, it offered a protected anchorage, and it had the relatively stable and predictable meteorological and oceanographic conditions considered essential to operations in which the unknowns loomed so large. Three test detonations originally were projected; two ultimately were carried out. The first, Test Able, was an airdrop of an atomic bomb on July 1, 1946, over a test fleet of 70 ships anchored in Bikini Lagoon. The second, Test Baker, was the detonation on July 25 of an atomic device suspended in the lagoon 90 feet below a small target vessel.

Scientific Interests

Although Crossroads was a military program, the mobilization of scientific interests was in many ways of historic proportions. For months before the explosions, oceanographers studied the waters and the structure of the mid-Pacific basin and meteorologists the winds and upper airs. Geologists, zoologists, botanists, and other specialists examined the atoll in detail. Bikini became, as it remains to this day, one of the most thoroughly familiar ocean structures in the world.

There was awareness, even then, of the significance of radioactivity as an element of nuclear effect. The task force made elaborate preparations to assure the safety of personnel and sent to the atoll thousands of radiation-detection instruments. Plans were made to observe the effects of radioactivity on test animals placed on ships of the target fleet.

The Underwater Detonation

The first of the Bikini events, Test Able, the explosion of a bomb dropped from an aircraft over the target fleet, sank a number of major vessels, left others sinking or crippled, contaminated many with radiation, and laid a plume of fallout northward over the rim of the atoll into the waters of the ocean. It was Test Baker, however, the underwater explosion, that would make Bikini the subject of radiobiological investigations for many years.

The Baker test was the first occasion in which nuclear debris was mixed with water and ocean sludge and returned to the area of detonation. The explosive device was of what later would be called nominal size, its force equivalent to 20,000 tons of TNT. The test still is regarded as a classic demonstration of the phenomena of shallow-water atomic explosion.

The Baker Test. A cauliflower-shaped cloud, after dumping one million tons of water that had been sucked up by the explosion, rises over the target warships, silhouetted in front of the spreading base surge.

At the moment of release, the surface water of the lagoon was first lifted and then penetrated by a lighted bubble that vanished in seconds in a hollow column of water of gigantic dimensions—a column 2000 feet in diameter (its walls 300 feet thick) rising to a height of 6000 feet and containing 1,000,000 tons of water. At the base of the column, foam was churned upward for several hundred feet, and, moving out from the base, as the column sank back into the lagoon, surged a monstrous wave initially more than 80 feet high.

Radioactivity in the water was intense. The immediate total was described as equal to “many hundred tons of radium”. Decay and dilution of radioactive materials quickly reduced the total radioactivity. After