In Arlington National Cemetery lies Captain Jimmy Priestly Robinson of the US Air Force, Distinguished Flying Cross, Purple Heart, and Air Medal. It celebrates a pilot who flew into a hydrogen bomb’s mushroom cloud to give the world two new elements. By 1952, the world knew of 98 elements, the last six had been created at the University of California, Berkeley, mainly by chemist Glenn Seaborg, by bombarding nuclei with light ions or neutrons.
This technique hoped for neutrons to be ‘captured’ by the nucleus and for the element to then undergo beta decay, turning a neutron into a proton and moving the target atom one place up the periodic table. But neutron capture is rare; when a neutron does strike a nucleus, it’s far more likely to cause it to break apart. This process, known as nuclear fission, releases of massive amounts of energy; enough to power an atomic bomb.
The U.S. military had been using planes, usually staffed with scientists, to sample debris from atomic blasts since the earliest nuclear explosions. The 28-year-old Jimmy Robinson, who had been shot down over Romania in 1944 and spent 10 weeks as a prisoner of war, was about to undertake the most perilous mission of his career. Robinson and the rest of his team were heading into the mushroom cloud.
An hour earlier, at 7:15 a.m. local time, “Mike”—the world’s first hydrogen bomb—had been detonated on the island of Elugelab[1], on the northern bend of the atoll. The first nuclear test, in July 1945, was witnessed from the air by future Nobel Prize–winning physicist Luis Alvarez (who also witnessed the dropping of the atomic bomb on Hiroshima). Unmanned drones were also flown into atomic clouds to take samples during test detonations, their controllers hoping for insights into the new superweapon
On May 14, 1948, a B-29 bomber piloted by Lieutenant Colonel Paul Fackler flew through a spur of gas that had drifted away from an atomic test. Never knowing whether it was an accident or not and that no one was hurt gave the Air Force the evidence they needed to send pilots inside.
Nuclear Bomb
A nuclear bomb uses fission, each atom exploding and releasing neutrons that collide with neighboring atoms, overloading them and causing them to detonate—a chain reaction. But this isn’t a perfect process: much of the potential fuel of the first generation of nuclear weapons was wasted, and so in reality the detonations were significantly smaller than their theoretical yield.
Hydrogen Bomb
A hydrogen bomb, the brainchild of physicists Edward Teller and Stanislaw Ulam, worked differently. Teller and Ulam added deuterium and tritium—neutron-rich isotopes of hydrogen—to the bomb to generate a two-stage explosion that created an even greater blast. Mike detonated with a force of about 10.4 megatons—around 700 times more powerful than the bomb that had destroyed Hiroshima seven years earlier.
A three-mile-wide fireball stretched across the horizon like a second sun and wiped Elugelab from the map, leaving a 164-foot-deep crater on the ocean floor. In less than 90 seconds the mushroom cloud soared above 55,000 feet—the maximum ceiling for the Thunderjet—and eventually spread 25 miles high and 100 miles wide.
The Pilots
The four pilots were all war veterans who had kept their cool in hostile skies. Their leader, Virgil Meroney, had shot down 10 German aircraft. Robinson, in Red-4, had spent the war as a bombardier of Dazzlin’ Dutchess, a B-24 Liberator, before he was shot down over Romania. Parachuting free of the burning wreck, he had calmly lit a cigarette as he drifted back to Earth. After the war, he had transferred to fighter jets and had already made a practice run through a smaller atomic blast in Nevada.
Three groups of planes would pierce the cloud’s interior that morning; the first made up of four planes was code-named Red Flight and took off from a remote strip on Enewetak Island, at the far southeast of the atoll that bore the same name. After five minutes the radiation instruments had “hit the peg”: whatever was in the stem of the cloud was greater than his plane could measure. Meroney broke free of the stem, paired up with his wingman, and ordered Robinson in Red-4 and pilot Bob Hagan in Red-3 to make their run. Meroney radioed across a final warning as the pair disappeared: “Don’t go in too far.” From Robinson, there came only heavy breathing. He had hit a pocket of severe turbulence almost immediately on entering the radioactive smoke, making his plane spin out of control. Battling against the yoke, he accidentally hit his microphone, broadcasting his struggles for control and consciousness.
Finally, mercifully, he wrestled control of the plane at 20,000 feet. Meroney ordered Robinson and Hagan to exit the cloud immediately and find the tanker plane for refueling. The four men had done all they could. Under the oppressive darkness of Mike’s still-burgeoning cloud, they were unable to spot the tanker; the bomb’s electromagnetic storm had scrambled their instruments, so they couldn’t lock onto the homing beacon from the airstrip at Enewetak.
Lost in the Pacific, the two pilots searched for a place to land, but their efforts were hampered by rain squalls and limited visibility. By the time they spotted the field at Enewetak, they were almost out of fuel. Hagan made his approach first, and with extraordinary skill, he glided his plane onto the runway in a dead-stick landing, bursting a tire on impact. Robinson was less fortunate.
His engine flamed out 3½ miles short of safety, leaving him no option but to try to land on the ocean surface and hope a rescue helicopter could get to him in time. His plane hit the water, bounced, and flipped. The chopper arrived just as the plane slipped beneath the surface; all that remained was an oil slick, a glove, and some maps. A year later Robinson was posthumously awarded the Distinguished Flying Cross. He was 28 years old and left behind a wife and a baby daughter. As a casualty of a secret atomic test, he did not receive a memorial in Arlington until 2002.
The Elements – 99 (Es) Einsteinium and 100 (Fm) Fermium
While rescue helicopters searched for Robinson, the filters from the other planes were recovered and shipped back to Los Alamos, US for analysis. There, scientists detected signs of the undiscovered isotope Pu-244, with a half-life of 80 million years. News reached Seaborg at Berkeley, whose team realized that, with the detection limits of the mass spectrometers at Los Alamos, the Pu-244 must have made up at least 0.1% of the sample. That meant other, even heavier elements would almost certainly have been created through neutron capture in the Ivy Mike blast. The Berkeley group managed to persuade a former colleague to give them half of one filter taken from the sampling planes. In less than a month, careful analysis of the filter detected the then-unknown elements 99 and 100. The top-secret nature of the discovery meant it wasn’t revealed until 1955 when the team was able to synthesize the new elements in the laboratory. They were named einsteinium and fermium. They were the first elements discovered by nuclear testing, and probably the last. ‘While there might be some interesting advantages to science to doing such tests, it is probably better for the world that they are not done,’ Alex Wellerstein, a science historian at the Stevens Institute of Technology in New Jersey says. ‘They accelerate the arms race, and it is probably more important to the human species that we avoid that than the benefit that such knowledge would bring us.’ And yet their discovery opened up a new era in nuclear research, which has led to the 118 elements we know today. Other created elements have found roles in treating cancer, providing energy, and powering life-saving devices, such as smoke alarms.
Footnotes
- Elugelab, or Elugelap, was an island, part of the Enewetak Atoll in the Marshall Islands. It was destroyed by the world’s first true hydrogen bomb test on 1 November 1952, a test which was codenamed shot “Mike” of Operation Ivy. Prior to being destroyed, the island was described as “just another small naked island of the atoll”. The fireball created by Ivy Mike had a maximum diameter of 3.60 to 4.08 miles. This maximum is reached a number of seconds after the detonation and during this time the hot fireball invariably rises due to buoyancy. While still relatively close to the ground, the fireball had yet to reach its maximum dimensions and was thus approximately 3.2 miles wide. The detonation produced a crater 6,200 ft in diameter and 160 ft deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to 20 ft high stripped the test islands clean of vegetation, as observed by a helicopter survey within 60 minutes after the test, by which time the mushroom cloud had blown away. The island “became dust and ash, pulled upward to form a mushroom cloud that rose about twenty-seven miles into the sky.” The outcome of the test was reported to incoming president Eisenhower by Atomic Energy Commission Chairman, Gordon Dean, as follows: “The island of Elugelab is missing!”. [Back]
Further Reading
Sources
Chemistry World
Science History Institute
