Thirty seconds after the first atomic bomb exploded, the shock wave rolled over Ben Benjamin, who was manning an array of cameras atop a bunker six miles west of Ground Zero.
“It just blasted the hell out of us,” Benjamin told a Laboratory audience Tuesday at a Heritage Series Lecture in the Administration Building Auditorium at Technical Area 3. “It heated you up from head to toe.”
Benjamin, a key member of the U.S. Army contingent at Los Alamos during the Manhattan Project, showed dozens of photographs of life and work in the desert of the Jornada del Muerte during the feverish preparations for the Trinity Test of July 16, 1945.
Benjamin worked for Julian Mack, a physics professor from the University of Wisconsin and leader of the wartime Laboratory’s Photo-Optical group. Julian and his deputy, Berlyn Brixner, pulled out all the stops in their efforts to record Trinity on every type of camera and instrument available at the time, Benjamin said.
“People were developing all kinds of gadgetry that had to work very rapidly,” he said.
Recruited mysteriously in 1944 after eight months as an Army private at the Carnegie Tech Engineering School in Pittsburgh, Benjamin was told only that he would be serving within the continental United States, that he would not be able to visit relatives or friends and that all his mail would be inspected.
When he received his travel orders to report to “Lamy, New Mexico and vicinity,” he took a train from Tennessee, and then was transported up the Hill by civilians in a black Buick who wouldn’t tell him anything other than, “When people go behind that fence, we never see them again.”
Benjamin recounted the tight security and unusual structure of Manhattan Project Los Alamos, where he took his orders from civilians rather than Army officers. One of his first jobs was at S-site, photographing the machining of explosives, despite his skepticism about the safety of such work.
Military police patrolled the McDonald Ranch shacks where Sgt. Benjamin and his co-workers lived, but they managed to sneak off to Las Cruces for beers and to explore some of the desert terrain surrounding what would become the Trinity Site. Ernie Wallace attached a box to the back of his Jeep and captured some of the many rattlesnakes that slithered around the test area. One night, an animal burrowed into the shack where the snakes were housed, letting them escape into the camp where the morning air was pierced by loud howls from the G.I.s.
“It was hotter than blazes down there in the summer,” Benjamin said, describing how he and his fellow soldiers rigged up a pump at a broken-down windmill and dry stock tank to create a swimming pool. “If there were any pleasant things to do in the evenings, we had to do them ourselves.”
Benjamin described many of the innovations Mack and his group came up with to overcome the anticipated saturation light from the bomb and give themselves every possible chance to capture the first mushroom cloud in history.
They removed 50-caliber machine guns from their turrets and replaced them with cameras capable of operating at an astounding 4,100 frames a second. They set K-17 aerial cameras 20 miles away to obtain panoramic views of the test. They installed streak cameras at one station and set off explosives at pre-measured intervals from Ground Zero to track the spread of the shock wave.
Most importantly, they adapted Mitchell cameras — standard gear for the Hollywood cameramen of the day — with adjustable shutters and souped them up so they could capture 100 frames in a second instead of 24, while equipping them with double-sized, 1,000-foot magazines.
Individual frames from the Mitchell cameras became the source for most of the images of Trinity with which the world is now familiar. However, the Fastex cameras that Benjamin and his colleagues operated from atop their bunkers six miles away from revealed the secrets of the bomb.
“The physicists went nuts over these kinds of pictures because they showed the growth of the fireball,” Benjamin said proudly.
When the gadget ignited, Benjamin shielded his eyes with welder’s glass for a few seconds, then looked out across the desert.
“My God, that is beautiful,” he recalled saying.
Mack disagreed. “He said, ‘No, it is terrible.’ ”
Benjamin explained that his first thoughts were of the tremendous spectacle and of the successful realization of all the hard work by the scientists and the soldiers, while Mack was struck by the bomb’s terrible, destructive power.
Benjamin was discharged from the Army in February 1946 and earned a degree in mechanical engineering the following year. He returned to New Mexico in 1948, and spent a 40-year career in field testing at Sandia National Laboratories. In fact, he witnessed the penultimate U.S. nuclear test in history, Hunter’s Trophy, on September 18, 1992, as a Sandia consultant.
