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Air Force personnel decontaminate a B-29 sampler aircraft with Gunk degreaser. (Courtesy National Nuclear Security Administration / Nevada Site Office)

Into the Mushroom Cloud

Most pilots would head away from a thermonuclear explosion.

The men chosen for the missions had a lot of flying hours, usually including combat experience. Both Jimmy Robinson and Bob Hagan were World War II veterans; Robinson had been a B-24 pilot who had been shot down over Romania and done time as a prisoner of war, while Hagan had flown almost 100 ground support missions in a P-47 with the Ninth Air Force. Pleased to be picked for such an important job, the pilots shrugged off the possible dangers: “You know, young and dumb,” Hagan laughs. But aside from great stick-and-rudder skills and exceptional instrument flying ability, a sampling pilot needed a knack for what’s now called multi-tasking.

Paul Guthals, one of the cloud sampling project leaders at Los Alamos, explained in the Air Force history publication: “Pilots with the ability to succeed in sampling missions were difficult to find. They had to possess the ability to receive radioed instructions, make taped recordings of instrument readings, be alert for excessive radiation and myriad other details simultaneously.... Most pilots with less experience and proven ability were simply overwhelmed—so badly that they could not function satisfactorily—by the awesomeness of the cloud interior.”

By most reports, the world inside an atomic cloud was a turbulent, glowing, brick red. On his mission, Hagan didn’t notice much color, but admits, “I didn’t pay much attention because I was flying instruments.” The reddish tint, from explosion byproducts such as nitrogen dioxide and iron oxides, provided pilots with a handy way to visually distinguish atomic clouds from cumulonimbus clouds.
Though they wore lead vests and their cockpits were usually lined in lead, the sampling crews soaked up more than their fair share of radiation—routinely far more than anyone else in the testing program. Besides the dose they received during the jaunts in the radioactive cloud, they continued to be bathed in radiation all the way home to base, sitting in an airplane coated with highly radioactive debris.

The choice of aircraft for the sampling missions was critical. The aircraft had to be fast, maneuverable, and easily modified to carry the sampling equipment. Particularly with the advent of the hydrogen bomb, it was also important that the aircraft be able to operate at high altitudes. Eventually, project leaders settled on two mainstays: the Republic F-84G fighter and the English Electric B-57 Canberra, built under license by Martin. Each met all the basic mission criteria and needed only a pilot and radiation officer, so fewer personnel were exposed to radiation. Later models of the B-57 had ceilings up to 60,000 feet, so the twin-engine jet bomber became the cloud sampling workhorse.

After a mission, the pilots parked in an area removed from the normal flightline of the Nevada or Pacific testing site airstrip. But the crewmen couldn’t just pop the canopy and hop out. Any direct contact with the airplane’s exterior was hazardous. They had to shut down their engines and wait until a ground crew, in decontamination suits, approached with a forklift that would raise a platform to cockpit level. The pilot and radiation safety officer would step carefully out of the cockpit and onto the platform, taking care not to touch the aircraft’s skin. After being returned to the ground some distance away, the crews were checked for contamination and directed to strip and shower immediately, repeating the procedure until Geiger counters stopped their furious clicking. The crewmen were given fresh clothing, while their contaminated gear, along with the radiation dosimeters they’d worn during the mission, were carefully packed up and sent away for analysis.

Meanwhile, five-man filter recovery crews used 10-foot poles to unlatch the sample boxes, remove the filters, and place them in lead-lined containers for shipment back to the labs. It took a certain amount of finesse and manual dexterity. “You wore lead-lined gloves and a vest, which probably did no good,” recalls ground crew vet Lou Watts, who thinks many of his cohorts died early of cancer and sees some correlation. “All the ones that went to the ’56 tests in the Pacific that I kept track of are gone.”

Maintenance crews then thoroughly washed down the aircraft and scrubbed it clean of radioactive debris, using both soap and water and a cleaning compound called Gunk—although not even Gunk could render a contaminated airplane pristine. The best that could be done was to cleanse it to a reasonably low level of radioactivity, then let the remaining particles naturally decay. But because of the frantic pace of the testing program, most aircraft never sat idle long enough to completely cool off.

And some parts of an aircraft simply couldn’t be reached. “You couldn’t wash the inside of the engines,” notes aircraft mechanic David Ellis. Pilot Langford Harrison told Carole Gallagher, author of American Ground Zero, that “since engines are oily by nature, they never did get the radiation out. They’d leave them out there for two or three days and then bring them back into service, emitting radiation like there was no tomorrow. We’d crawl into those things and fly through the cloud again…the same aircraft over and over. They should have been burned along with our clothes.”

As the nukes kept detonating over Nevada and Enewetak and the cold war intensified, Atomic Energy Commission scientists argued with the Air Force over just how much radiation was too much. In 1951, when manned testing began, the AEC had specified that personnel participating in test operations could safely receive up to 3.9 roentgens of gamma radiation over three months. Once an individual had reached that level, he would be banned from further exposure until the remainder of the three months had passed.

That was the theory. In practice, the policy proved troublesome, particularly for the Air Force, which admitted as much in its official history of the sampling program: “The enforcement of radiological safety measures…was a continuing problem, with outright rebellion by Air Force operational leaders threatened on at least one occasion. They argued that no serious mishaps had occurred and that application of accepted radiological safety measures unnecessarily upped the requirements for manpower, lessened the readiness of crews and aircraft for tests, and that all decontamination program protection measures in use were more than actually required to insure safety.”

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