Sixty years ago, this summer, the ground shook and the sky was ablaze in southern Nevada. One after another, powerful atomic explosions rattled the Nevada Test Site north of Las Vegas. It was the most intense series of nuclear tests in American history.

Among the artifacts that survived intact is a piece of World War II naval history that seems very out of place in the desert. The I-Team was allowed into the facility for a look around. 

It was a grim and tense era. The summer of 1957 saw one mushroom cloud after another, billowing high into the sky. Between late May and early October, 29 atomic fireballs pierced the atmosphere of the Nevada Test site. Staying ahead of the Russians was primary objective, not historical preservation.

But now, decades later, one historical mystery has been resolved by a physicist-turned-gumshoe.

The code name was Operation Plumbob. Atomic fireballs shredded the sky almost weekly. The security of the planet hung in the balance. These explosions obliterated pretty much anything within range — almost.

Livermore lab physicist Rob Hoffman first saw the odd relic two years ago during a tour of the Nevada National Security Site.

“I thought it was a funny looking trailer, as a matter of fact. But the closer I got, the more it looked like it belonged on a ship at one time,” said Rob Hoffman, physicist, Lawrence Livermore Lab.

Hoffman, who is from a navy family, was right. It’s a gun turret from a heavy cruiser. During World War II, heavy cruisers were often in the thick of the deadliest sea battles. So, what’s it doing in the desert of Area 2, in a spot that 60 years ago would have been battered by multiple atomic blasts? The barrel isn’t a gun. It’s a detection device designed to collect and analyze light.

“The idea behind it was to find out how well a nuclear weapon design functioned,” Hoffman said.

The turret was the answer to an engineering challenge. During Plumbob’s frequent tests, test site workers had to build detection bunkers, filled with equipment, for each blast. They dug trenches, some 20 feet wide, 20 feet deep, and up to a mile long, for the coax cable that connected the detection gear. The trenches were then refilled to protect the cable from being vaporized. 

A contractor named Erv Woodward had the bright idea.

“That if you could make a reusable line of sight with something that could protect the detectors but could point at each of the devices as they are scattered around here, then they wouldn’t have to lay so much cable, wouldn’t have to make so many special purpose bunkers and they might even save some money,” Hoffman said.

Woodward and colleagues went to the Mare Island shipyard in San Francisco, found a couple of turrets sitting on a dock, and chose it. It was transported south by ship, then was loaded onto trucks, and likely generated stares as it traveled the new Interstate highway 15 to the Nevada Test Site. It had to be modified considerably, the 8-inch gun barrels were removed, and the assembly was mounted on a foundation that allowed it to rotate 360 degrees.

“This was pointed at the device sitting on a tower, light would shine through this tube in the turret, safe from the blast wave less than a mile away,” Hoffman said.

Diablo was the first. An atomic device detonated from a tower north of the turret (July 15, 1957) followed by Shasta (Aug.18) to the south and Whitney (Sept. 23) to the west. In between, the turret collected data from the Smoky test (Aug. 31) uncorked in area 9 further away.

“It worked like a piece of cake, like a charm, got great data out of it,” Hoffman said.

The turret survived the tests and the elements. Today, it sits in obscurity, home to ferocious test site termites and other curious critters. In the 90’s, test site archeologists collected information about the turret, but there was one big question that remained unanswered.

“But they couldn’t tell me what ship it came off and being from a navy family, it caught my imagination,” Hoffman said. “If you look closely, you can see it had rough treatment.”

The sprawling test site is littered with  remnants of seemingly odd objects  once used in atomic tests, department store mannequins, the stubble of the atomic forest, the rubble of obliterated buildings. but this gun turret got Hoffman’s full attention because no one could answer a key question.

“They couldn’t tell me what ship it came off of,” he said.

The turret was used as a movable sensor station during four atomic tests in 1957, three of the devices were detonated within a mile of the thick metal structure. Those explosions, plus six decades of baking in the  blistering hot desert, have worn it down a bit, but Hoffman noticed evidence of another kind of trauma –indications that the turret had been in combat.

“On top this piece here, this green piece, had to have been replaced. The entire piece was blown into the turret when the bomb of the kamikaze hit,” he said.

Test site officials have long known the turret was obtained from a naval shipyard in San Francisco, that it most likely had been made for a cruiser. Fifty or more of these heavy cruisers saw action during World War II, but only 10 were built with this type of turret. It wasn’t until Hoffman applied his detective skills and dug into various historical archives, no one could say for sure the name of the ship.

He studied the tell tale scars on the turret, then compared them to combat records from the wartime cruisers. One by one, he eliminated names.

“Every one of those ships served with distinction. Some didn’t last long. Four were lost to enemy action. Two of them were expended due to friendly fire in Operation Crossroads which was the first atomic test after World War II,” Hoffman said.

A faded inscription on a hatch door suggested the turret was form the U.S.S. Pensacola, but Hoffman determined the door was itself a repair added later. The clincher for Hoffman was a chiseled inscription he found on the side of the turret which matched shipyard records he’d found.

“The ship it came off of was the U.S.S. Louisville, just like the Louisville Slugger.

A slugger is right. The Louisville engaged in some of the deadliest naval battles of the war. Hoffman tracked down three crew members who confirmed to him how some of the damage was inflicted.

“A kamikaze airplane landed on top of it, just on the left side here. A bomb went off on the left side here just as the plane hit the turret,” Hoffman explained.

Information on the U.S.S. Louisville

During a battle off the Philippines in Jan. 1945, in a two-day period, the Louisville was hit by desperate kamikazes twice. The second deadly attack was recorded on film, and there is original footage. It’s been slowed down. The kamikaze slams directly into the top of the turret, setting off a bomb and a fireball. Thirty eight crewmen died. More than 100 suffered burns, including the ship’s captain. The Louisville stayed in the fight for another day before heading for repairs. The sailors were buried at sea.

“When she came back, they wanted to turn her around fast. They had a spare turret. They pulled the old one off, put the new one in, sent her back out and she got hit a third time. When she went to Okinawa, another kamikaze, so three times,” Hoffman said.

The turret that was hit by the kamikaze was repaired, but the war ended before it was needed again. It sat on a dock for 10 years before it was picked for a special job at the Nevada Test Site. The U.S.S. Louisville was mothballed and eventually was sold for scrap, but a piece of it is still around.

The Mystery of the Gun Turret in the Desert – R.D. Hoffman & J.R. Leslie

“It’s a piece of history. You drive by here and never see. We almost lost it,” Hoffman said.

Hoffman proposed putting a plaque on the turret so that its history would be preserved for the future and it looks like the NNSA, the agency which oversees the test site, is moving forward with that plan.