Declassified: How cold war movies are blowing up atomic bomb models

Thousands of blasts from the past are teaching nuclear physicists new lessons about old physics.

Scientists and film experts are teaming up to save a treasure trove of cold war-era nuclear test footage, teetering on the brink of decomposition. By digitizing the records and applying current video analysis, the team has learned we don’t know quite as much as we thought we did about atomic bombs.

The United States carried out hundreds of aboveground nuclear tests between 1945 and the early 1960s, when they were banned. Recording more than 10,000 videos from various angles, the government strived to glean every last bit of scientific information possible about the deadly new technology.

But the effort was laborious, and imprecise by modern standards. As many as 1,000 experts carried out manual analysis in the '50s and '60s, painstakingly advancing the clips frame by frame and eyeballing the infernos' sizes, which together with timestamps allowed calculation of other characteristics, such as speed and yield.  

An international treaty banned such atmospheric tests in 1963, so now researchers simulate digital blasts on supercomputers, which still rely on the data gathered from the original recordings.

“We don’t have any experimental data for modern weapons in the atmosphere. The only data that we have are these old tests,” Gregg Spriggs, a government nuclear weapons physicist, says in a video from The Lawrence Livermore National Laboratory. 

And those recordings, along with the scientific data contained, were about to be lost forever.

The film canisters had reportedly begun to give off a vinegary smell, a sure sign they were breaking down. “We know these films are on the brink of decomposing to the point where they’ll become useless,” Dr. Spriggs, who spearheaded the The Lawrence Livermore National Laboratory’s effort to digitize the videos, says in the video.

The laboratory brought in Jim Moye, a film expert with more than 40 years of experience who helped with the preservation of former President John F. Kennedy's assassination video.

With the aid of special equipment capable of scanning the obsolete and deteriorating celluloid, the team noticed something was off when they started preserving the movies.

“When we found out that most of the data that had been published was wrong, then we decided we needed to rescan and reanalyze all the films,” explained Spriggs.  

Video analysis has advanced considerably since the nuclear age, when individually inspecting the nearly 5,000 frames in a two-second clip could take all day. Thanks to custom coded Matlab and Python tools, a computer can now pull off the same task more accurately in a matter of minutes. With just a few hundred videos analyzed, the team is already uncovering revelations.

"We were finding that some of these answers were off by 20, maybe 30, percent," Spriggs told NPR. "One of the payoffs of this project is that we're now getting very consistent answers. We've also discovered new things about these detonations that have never been seen before. New correlations are now being used by the nuclear forensics community, for example."

And they’ve still got a long way to go. Spriggs estimates it’s taken years to locate about 6,500 of the original 10,000 videos. They’ve scanned a little more than 4,200 films, and analyzed “just a small fraction of those.”

Far more than a history project, the initiative is highly relevant to contemporary science and current efforts to modernize the nuclear arsenal.

“We need to be able to validate our codes and trust that the answers that are being calculated are correct,” Spriggs told the site Laboratory Equipment. “The legacy that I’d like to leave behind is a set of benchmark data that can be used by future weapon physicists to make sure that our codes are correct so that the U.S. remains prepared.”

The lab has also uploaded select videos to Youtube, where you can check out the entire playlist.

The clips, which range from seconds to minutes in length, record dozens of cataclysmic blasts in perfect, eerie silence. Spriggs hopes they’ll serve as a visceral reminder of the weapons’ power in the modern era.

“I think that if we capture the history of this and show what the force of these weapons [is] and how much devastation they can wreak, then maybe people will be reluctant to use them,” he told NPR.