The rain gradually cleared and the men were ordered to their viewing positions. The word spread: “It’s go!” The men faced the sea, their myriad cigarette ends glowing darkly red like fading fireflies. There were nervous chuckles and a few bad jokes, but an almost supernatural stillness descended as the first roar of the Valiant engines signaled the start of the operation.
Meanwhile Ralph Gray was scratching his head over the fact his ‘few gentlemen’ seemed to have vanished in the night. “I walked over to their tents, but they were all empty. Even the guards had gone. They had all packed up in the night and departed without telling me. And I knew they were not coming back because all their clothing and personal belongings had disappeared with them. All that was left was the smell of tobacco smoke and some half empty gin glasses. I walked across to the other tents and spoke to an officer who told me they had gone somewhere safe… very safe. He told me not to ask questions and advised me to make for a small corrugated iron Nissan hut near the beach.”
Gray wasn’t to know, but Penney and most of his entourage had boarded two Dakota aircraft that ground crew had prepared for take-off. Just before the scheduled time for the bomb drop, the aircraft took off and headed south toward Malden Island, 400 miles away. The flight is recorded in the Operations Record Book. The log reports that eight people were aboard, although they were not mentioned by name. But at least one aircraftsman noted the portly figure of William Penney boarding the lead Dakota.
The countdown was delayed by one and a half hours, and Valiant XD825 was finally swung into position just as the sun broke through. Its whiteness dazzled onlookers as it reached the centre of the runway. With a tremendous roar the engines revved changing soon to a high-pitched scream as the plane picked up speed.
At Port Camp hundreds of men were ordered on to the landing craft moored in the shallows. Scores were crammed into each vessel and there was standing room only. There was much nervous laughter as the ungainly craft bobbed about in the swell, the men hardly able to move.
Archie Ross recalled: “It was ludicrous really because if the Valiant did crash on takeoff, God alone knows what we would have done. The landing craft were just not suitable for putting to sea. They would have been swamped as soon as they reached the big rollers breaking a hundred yards from the shore.”
There was an audible sigh of relief from onlookers all over the island as XD825, piloted by Squadron Leader Bob Bates with its 8,000 pound load, rose smoothly into the air and headed into the blue. It was followed by the other Valiant, the grandstand aircraft that would take up position a mile behind to film the bomb drop. Finally the five Canberras of 76 Squadron took off in quick succession. Three circled the proposed dropping zone. These were to act as spotters, sniffing out the highest concentrations of radiation. Two others flew a hundred miles downwind ready to track the onward migration of the cloud as it drifted over the Pacific ocean.
Canberra WH980, with Flt Lt Eric Denson at the controls, was the last to go. His aircraft like the rest was smothered with a sticky, cream substance that had the consistency of molasses. This ‘protective varnish’ had been invented by the atomic weapons research boffins back at Harwell, and was designed to absorb radioactive fallout leaving the interior of the aircraft relatively clean. At least that was the theory. Denson took WH980 straight up to 40,000 feet and waited. Then into his headset a harsh metallic voice announced, “Bomb gone…”
On the ground, speakers mounted on tall poles, announced in their tinny, alien voices, the countdown. The metronome voice marked off the seconds like footsteps on the gallows.
As Grapple Y was released from the bomb shackle and began its fall, it automatically turned on the telemetry recording instruments that were focused on the point in space where the bomb was planned to explode, some 8,000 feet above the ocean. Its release from the shackle also switched on the clockwork timing mechanism which would set off the firing sequence. Extensions to the fins on the tail of the bomb snapped into place and began to damp down its oscillations to a graceful arc through the morning sunlight.
The firing sequence began a series of events lasting only a few millionths of a second. At 42 seconds, the uranium-rich atomic core exploded followed almost immediately by the high explosive supercharge, squeezing the beryllium tamper. This in turn crushed the lithium deuteride fuel with enormous force, reducing it to a ball of super-dense liquid metal as hot as the centre of the sun. The core now went into an uncontrolled chain reaction. This implosion phase had taken some 70 millionths of a second. The explosion phase followed at 300 millionths of second.
FIRE!
A light so bright and white it could only have come from the very heart of creation momentarily turned the island and every man and creature upon it into stone. Then, with a whiplash snap, the light was gone to be replaced by a steadily rising heat as though someone was slowly opening the door to a gigantic furnace. The men lined up in quaking masses slowly turned to each other, an unspoken question on their lips: “Where’s the bang?” But there was no sound at all… No birdsong, no wave crashing. It was as though the universe was holding its breath.
Thousands of indigenous frigate birds nesting near the southern tip of the island where the bomb exploded were the first casualties. They were turned instantly into blazing flying feather balls or incinerated on their nests. Next, large shoals of dead and dying fish floated to the surface as huge areas of the ocean boiled. Lush green vegetation withered instantly as though irrigated with boiling acid, and palm trees lashed furiously about before snapping like dry twigs.
The eerie silence that followed the blast remained unbroken for a minute, but it seemed like hours. Most of the men were on their feet now, thinking it was all over. Suddenly the loudest bang anyone had ever heard rent the air like the crack of doom. The noise sent everyone crashing to the ground and the men could only watch helplessly in goggle-eyed awe as on the horizon a dark shadow, rippling like billions of tiny fish, formed and raced toward them with terrifying speed.
The realisation hit home that the blast wave was about to overwhelm them. Panic set in. Men threw themselves about in desperation. Some began a futile run for shelter. Too late, the blast wave like a giant hand, slapped down…”
Ken McGinley, a young Royal Engineer who had arrived on the island along with a thousand other troops on the Dunera a month earlier, was sitting on the beach when he heard a roar “like a thousand stampeding horses” as the blast wave approached: “We had had a talk from an officer on what we could expect, but nothing compared me for this. This was the daddy of all bombs. There was something incredible sinister about this shimmering line of energy skimming over the ocean with amazing speed. I dived to the ground and as it hit I felt an impact and a crack like lightning had hit close by. The huge fireball forming above me seemed to stretch from horizon to horizon. I knew straight away we were far closer than we should have been for a bomb that size. It was truly awesome; a great rolling, roiling, boiling mass of fire. Then a spout seemed to rise from the ground and the familiar mushroom cloud began to form.”
Archie Ross: “To be honest, I considered myself a bit of a cool dude. I remember being mildly surprised when the impact of the blast wave hit and my goggles were slapped against my face. Some people near me were panicking but I felt sort of detached. But then things began to happen that made me realise just how small and insignificant I was when compared with the forces of nature. I still remember, as though it was yesterday, the stem of the mushroom cloud reaching down to the sea and the waves parting like that famous scene from the film the Ten Commandments when Moses causes the Red Sea to part. I remember seeing the water rushing up the spout, followed by all the mud and sand from the seabed, all being sucked up into the cloud like a giant vacuum cleaner. I remember the cloud spreading and becoming a hellish green on the underside…”