Superheavy

by Kit Chapman

  4 Cherwell was being snooty. Thanks to the likes of Humphry Davy, the British had discovered more elements than anyone else by cracking open rocks, zapping things with electrolysis or probing the air. Now the Americans were manufacturing them beyond the supposed boundaries of the periodic table. It just wasn’t cricket.

  5 Although the smoke detector is americium’s great contribution to modern living, actinide chemists often joke that they are constantly looking for new ways to ‘make americium great again’.

  CHAPTER SIX

  The Death of Jimmy Robinson

  The F-84 Thunderjet roared through the skies, the waters of the Pacific Ocean a smooth cerulean carpet stretching as far as the eye could see. Captain Jimmy Robinson swallowed hard, his own breath echoing inside the respirator, and steeled himself for the mission to come. The next few minutes would involve the most taxing manoeuvre of his career. Aged 28 years, Robinson was a seasoned pilot who had flown as bombardier in Liberator bombers during the Second World War. Even so, he knew there was little in his experience he could call upon for the task ahead. He was going to fly inside an atomic mushroom cloud.

  The F-84 was the US Air Force’s main fighter-bomber. A single seater, the body was shaped like a silver clipped cigar, with straight, flat wings ending with two smaller cigars on the tips. Early designs had been a nightmare to fly (the world was still transitioning from propellers to jets), but by 1951 the F-84 was a trusted part of America’s arsenal in the sky. It dominated the battlefields of the Korean War, its payloads accounting for about 60 per cent of all ground targets destroyed during the conflict. Although they were no match for the Soviet-built MiG-15s (those were left to the nimbler F-86 Sabres), F-84s would go on to fly over 86,000 missions, dropping some 55,000t of explosives. It sounds impressive until you know that Thunderjets can also drop nuclear weapons: a lone fighter could have delivered the equivalent of 20 times the entire war’s bombing campaign in a single run.

  Robinson was Red 4, part of a key element in a mission code-named Operation Ivy – the eighth series of US nuclear tests. Somewhere below his flightpath was Elugelab, a small islet that formed the northern bend of a 40-island horseshoe called Enewetak Atoll, today part of the Marshall Islands. There, at precisely 07.15 a.m. local time, 1 November 1952, the US detonated ‘Mike’. It was the world’s first thermonuclear bomb, capable of an explosion so vicious it would mimic the intense furnace of the Sun. Mike was the next generation of atomic design, the brainchild of Manhattan Project alumni Edward Teller and Stanislaw Ulam. Rather than just imploding like Trinity, the bomb had a second stage to feed more fuel and boost the chain reaction. As it used deuterium and tritium, heavy isotopes with only one proton, the world would come to know it as a ‘hydrogen bomb’.

  The US Air Force had discovered by chance that you could fly in a mushroom cloud: in May 1948 a B-29 bomber observing a nuclear test had found itself unable to avoid a finger-like spur kicked up by the explosion. The pilot, Lieutenant Colonel Paul Fackler, had cut through the atomic gloom, then swung into a few rain clouds to wash down his bird on the way home. ‘None of us keeled over dead and no one got sick,’ Fackler had reported smugly on his return. It was unclear if it had been an accident or a deliberate stunt, but Fackler had enjoyed the experience and requested permission to form a new squadron dedicated to repeating his feat, this time equipped with scientific instruments to take samples. There’s a saying in the military that the most dangerous thing you can do is give a superior officer a bright idea. Let’s make pilots fly through nuclear blasts on a regular basis for science. While Fackler petitioned the Pentagon, someone figured they’d just get fighter pilots to fill his flight boots.

  According to Paul Guthals, one of Los Alamos’s cloud sampling experts, it was hard to find pilots with the ‘right stuff’. In addition to flying the jet fighter – a machine that could kill you in seconds if you stopped paying attention – the selected airmen also had to run a suite of scientific equipment and recording devices. Three radiation instruments had to be monitored simultaneously, and their readings had to be both recorded on a sheet and read off to a scientist in the control aircraft outside the cloud. Each pilot also carried a stopwatch to time their duration in the cloud – and therefore their probable dose of radiation. This would have been difficult enough in clear skies, but they were being asked to do it at the heart of a radioactive dust storm. ‘Most pilots with less experience and ability were simply overwhelmed,’ Guthals noted in an article for the Newsletter for America’s Atomic Veterans, ‘and were often distracted by the awesomeness of the clouds’ ever-changing interior.’ Robinson had the guts and cool head in spades. During the Second World War he had been shot down over Bulgaria and forced to bail out, eventually ending up a prisoner of war in Romania; while parachuting down he had checked his maps, then calmly lit a cigarette as he’d waited to land. In April 1952 he had completed a practice sampling mission and proven a capable pilot. Even so, the hydrogen bomb was expected to be another prospect entirely.

  At 07.15 a.m. on 1 November 1952, Robinson was still on the tarmac at base with the other pilots. There, he watched a bright orange bloom, a perfect semicircle, push out from its epicentre to bathe the sky, lightning crackling around its flame. In a lingering visual scream, the light faded, leaving only the telltale mushroom cloud of dirt, sand and coral. The Ivy Mike explosion was beyond imagination, a looming hellscape painted throbbing red from nitrogen dioxide and iron oxides. At its base, Elugelab was gone: the islet had literally been blown off the map.

  Ninety minutes after detonation, Red Flight – the first of three flights that would go into the cloud that day – made their approach. The first two F-84s, led by Lieutenant Colonel Virgil Meroney, made their turn and flew inside. They were supposed to enter the mushroom’s top, but at 17,000m (55,000ft) it was too high for their planes; an F-84’s ceiling was only 12,000m (40,000ft). Instead, their only option was to fly into the stem, where the buffeting winds would be harshest and full of Elugelab’s remains. Five minutes later the first pair of fighters burst out, jet engines howling as they zoomed clear.

  By the time Robinson’s turn came, the mushroom cloud had plunged the atoll into an eerie darkness. In formation with his wingman, Bob Hagan, the two fighter pilots began their approach toward the cloud. One moment it was smooth sky, the next an ugly maelstrom. Meroney had radioed back that it was filled with a ‘red glow, like the inside of a red-hot furnace’ and that his instruments ‘went around like the sweep second hand on a watch’; Hagan described it as ‘both grey and dark shades and still appears to be boiling’. Robinson grappled against the turbulence of the mushroom cloud’s interior, his hands tightening on the yoke as the entire cockpit shook wildly in the crosswinds. The Thunderjet was being tossed about like a ragdoll in a washing machine, but gradually he was able to wrest back control and activate the autopilot.

  Inside the bulging wing tips of his F-84, filters had been set up to scoop up whatever particles might have been created in the blast. The heart of the explosion had been a near-instant flux of 1024 neutrons per cm2. Neutron capture was happening at a rate never seen before on Earth. Hungry nuclei were grabbing neutrons and remaining stable, forming isotopes as rich as uranium-255, 17 neutrons more than its most common variant, then beta-decaying into elements usually only present in merging neutron stars.

  Robinson had more pressing concerns. His instruments told him the sky in front was a no-go zone, a cauldron of hot gas and broken reef. Robinson twisted his fighter out of its path, forcing the autopilot to disengage. The dust cloud was clogging up the machinery and causing his fighter to shake itself apart. The fighter’s engines choked, coughed and stalled, the guttural growl flooding Robinson’s senses as his hunk of metal fell from the heavens. He lost altitude, lost control, fought against the g-force not to lose consciousness. Breathing became heavy, the noise of each lungful resounding over the radio as his finger pressed into the radio button. His sinews wrestled against the vibrations and resistanc
e even as cold sweat soaked his brow …

  The fighter recovered. Robinson pulled on the yoke, levelling the F-84 at 6,000m (20,000ft). Meroney ordered him to exit the cloud. Shortly after, Hagan joined him, once again in the vast emptiness of the Pacific. The churning hell was gone; the world was serene, colourful, endless blue. It had been an impressive piece of flying.

  An F-84 uses around 540kg (1,200lb) of fuel an hour. With atmospheric filters strapped to the wings, the sampler pilots hadn’t been able to carry reserve tanks, so had been told to head for a tanker aircraft to refuel. If they couldn’t find the tanker, they had been ordered to head south, back to the strip at Enewetak (the largest island in the atoll, at the eastern tip of the horseshoe) and land.

  When Robinson and Hagen emerged from the cloud, they each had around 450kg (1,000lb) of fuel remaining. It was then they realised the electromagnetic pulse inside the cloud had scrambled their electronics and neither pilot could find the radio beacons to guide them home. They were lost and low on fuel and could see only the deep waters below. By the time Hagen managed to pick up the beacon, they were down to 270kg (600lb) of fuel and were 154km (96 miles) north of salvation.

  The duo’s luck worsened. Rain squalls descended and limited visibility. By the time they located the field, their machines were running on vapours. ‘My gas gauge was on empty,’ Hagen recalled. ‘I was able to set up a pattern and land without fuel, using total deadstick manoeuvres.’ Hagen was underplaying his skill: landing after a flame-out took almost superhuman effort. He hit the tarmac hard, his tyre bursting on impact. It was messy but it worked.

  Enewetak was too far for Robinson. While still at 5,800m (19,000ft) he ran out of fuel; at 4,000m (13,000ft) his engine flamed out; at 1,500m (5,000ft) it was clear he wasn’t going to make the field. A rescue chopper had scrambled to pick him up, and Robinson weighed up his options. Bailing out with his parachute was possible, but his flight suit included a lead-lined vest, ironically as a safety precaution to limit radiation exposure. Trying for a water landing was equally dangerous, as an F-84 wasn’t designed for a life on the ocean.

  ‘I have the helicopter in sight and am bailing out,’ he reported, popping the canopy. They were his last words. Rather than abandon his plane, Robinson seems to have thought twice about the parachute jump and opted for a water landing instead. The emergency helicopter crew watched his plane dip its belly in the ocean, skip like a stone on a pond, hit a wave and flip. They made it to the crash site, about 5.5km (3.5 miles) north of the runway, just as the Thunderjet slipped beneath the surface. ‘The people in the tower told me that an airplane had just gone into the ocean behind me, and they didn’t see any signs of a parachute or anything else,’ Hagan remembered in the article for Newsletter for America’s Atomic Veterans. ‘Then, deep in my gut, I had a bad sinking feeling.’ All that remained on the surface was an oil slick, one glove and the waterlogged remains of several maps.

  Jimmy Priestly Robinson was the first person killed in the hunt for an element. Sadly, his body was never found. His colleagues expected as much: the water around Enewetak was deep, the chances of survival slim. A year later he was recognised as killed in action and posthumously awarded the Distinguished Flying Cross. By then, Fackler had persuaded the Pentagon to commission the 4926th Test Squadron (Sampling). The US would continue to fly planes into mushroom clouds until 1962.

  The Robinson family had to wait longer for answers. The secrecy of atomic work meant details about Robinson’s death fell into a bureaucratic black hole, with none of the US agencies willing to take up his case. His daughter became involved with veterans’ groups whose dwindling networks fought to keep his memory alive. Even so, it took 50 years before a memorial was erected in his name at Arlington National Cemetery. There, in 2002, his wife was finally given a folded flag in honour of his service.

  ‘You hear a lot about heroes,’ Robinson had told the Memphis Lion’s Club on his return from the Second World War. ‘I don’t believe in heroes.’

  I do. Jimmy Robinson was one.

  * * *

  Robinson’s death was not in vain. The other three fighters had survived the hell of the mushroom cloud, as had all of the flights that took off later, and their wing filters were rich with radioactive samples. In a nuclear blast, lighter particles fly to the top, heavier ones to the bottom. Unbeknown to the pilots, by flying through the stem, Red Flight’s filters had captured something never seen on Earth.

  The next steps were taken with meticulous care. Protocol at the time meant the pilots couldn’t touch the outer skin of their plane, so they had to wait for the ground crew to bring out a cherry picker. Then, while the flyboys stripped down and headed to the decontamination showers, five men (known as the ‘decon-grunts’) would use 3m (10ft) poles to open the wing pods, remove the filters and deposit them in lead-lined containers. Sealed and secret, the cargo would make its way back to the US as quickly as possible – the samples’ half-lives created a tight deadline.

  Once stateside, the filters went directly to Los Alamos, the lab in charge of analysing all nuclear debris. The standard practice for nuclear particles was to dissolve them in acid, but with Ivy Mike the coral from the reef made that tricky: the samples had a habit of catching fire. Tents were quickly erected outside the main building for the precarious work. Here, it soon became apparent that something special had happened. The filters contained something emitting alpha particles with energy levels much higher than any known isotope of plutonium.

  While the Los Alamos scientists got to work, some of the samples were sent on to Argonne and others to a new lab just outside San Francisco. Teller, with the support of Ernest Lawrence, had argued that concentrating all US nuclear weapons research in a single lab (Los Alamos) was unwise – and that a second lab would create some healthy competition. As an alternative, they had pitched a new facility in Livermore, a small town amid the golden hills Glenn and Helen Seaborg had driven through a decade earlier. It had been a perfect space to build an expansion of the Berkeley lab, and Teller had taken up residence there as bomb-maker in chief. Soon, the different teams confirmed Los Alamos’s findings and traced the ‘mysterious alpha’ emissions down to new isotopes, including Pu-244. This, everyone was amazed to find, had a half-life of 80 million years – meaning it was stable enough for trace amounts to exist naturally from when the Earth formed.

  The element team at Berkeley had nothing to do with Ivy Mike or the secretive work at Livermore. But winning a Nobel Prize gives you a little clout: Seaborg was a big shot, important enough to receive a secret teletype about the Ivy Mike detonation. The message mentioned that ‘data on the recent Eniwetok test indicates the presence of some unique heavy element isotopes such as Pu-244’. Seaborg understood what that meant immediately. The Ivy Mike explosion had acted like a nuclear cauldron, a particle accelerator and a nuclear reactor all rolled into one. If Pu-244 had been made, heavier elements were likely. Perhaps even elements beyond californium.

  Seaborg passed the news on and Al Ghiorso and Stanley Thompson made some rough calculations. The only way scientists at Los Alamos could have detected Pu-244 was by using a mass spectrograph. At the time, the best instruments were only sensitive enough to pick up Pu-244 if it made up about 0.1 per cent of a sample. In heavy element terms, that wasn’t gold dust: it was a veritable gold mine. There had to be traces of heavier elements present.

  Ghiorso and Thompson phoned Livermore. Kenneth Street, who had helped with californium, was there working with Teller. Calling in a favour, the pair convinced Street to hand them half of his filter paper. Seaborg was sceptical about the chance of discovering anything, but Ghiorso – just turned 37 – still felt young ‘and [was] not about to be deterred by what seemed like the impossible’.

  Taking their precious relic of the Ivy Mike blast, Berkeley Lab began their tests. Within minutes it was obvious that they had something that looked like element 100. Soon, they realised their mistake – it was element 99. From the time Seaborg had heard abo
ut the filter, to the discovery of a new element, had taken nine days. The team were dealing in the smallest quantities anywhere in the world. Californium, element 98, had been detected from 5,000 atoms. Element 99 was discovered from around 200 atoms. The team were quite literally plucking their prizes out of thin air.

  The discovery didn’t sit well with other labs, who felt they deserved equal credit. Over Christmas 1952 the entire US nuclear community began to turn on each other. Berkeley asked Argonne for more material; instead, they got a memo from Argonne claiming the lab had discovered element 100 from their Ivy Mike sample. On 15 January 1953 Berkeley also found what they believed was element 100 from the filter. The two labs began to argue.

  The politics of science can get messy – and fewer things are more hotly contested than who did what first. By February, Ghiorso wrote of being ‘tired of playing games with the Argonne crowd’. But Berkeley’s trump card was Seaborg: the Michigan chemist had matured into a masterful diplomat. He announced Berkeley’s sighting of element 100 to Argonne, but refused to tell them any specifics – preventing Argonne from adopting his team’s techniques. In the meantime, he sweet-talked Los Alamos into being recognised as co-discoverers of the elements with Berkeley. Argonne’s data soon turned out to be the exact error Berkeley had made: a misidentification of element 99. Seaborg’s quick-footedness had outfoxed the Midwest team.

  The problem was how to reveal the new elements. The Ivy Mike test results were classified; as with plutonium, the discovery couldn’t be announced publicly. Instead, Ghiorso and Thompson rolled up their sleeves. If you could make elements 99 and 100 in a bomb, maybe you could make them in a lab too? All they needed was to do it before someone else.