The US government has detonated hundreds upon hundreds of nuclear weapons in secret.
Researchers carried out above-ground blasts from 1945 up until 1963 — when the first nuclear test-ban treaty was signed.
The goals of the tests were straightforward: detonate new bomb designs, measure their explosive power (called yield), and see what might happen to enemies unfortunate enough to be a target.
About 10,000 videos of such tests were filmed, analysed, and locked away in high-security vaults, where they were nearly forgotten. Most started to decay over the decades.
However, more than 50 years later, a team of scientists at Lawrence Livermore National Laboratory (LLNL) is working day-in and day-out to rescue, scan, and analyse the high-speed films.
“This is it. We got to this project just in time,” Greg Spriggs, a nuclear-weapons physicist at LLNL, said in a video about the digitization effort. “We know that these films are on the brink of decomposing, to the point where they will become useless.”
Over the past five years, Spriggs’ team has scanned 6,500 films and declassified 750 of the never-before-seen videos. Several dozen have been uploaded to YouTube, with more on the way.
“These films are priceless to us,” Spriggs told Business Insider.
Here are some of the highlights from the videos, many of them recorded in the remote deserts of Nevada.
Most of the never-before-seen films released by LLNL are of high-altitude explosions like this one from October 1962.
This test, called 'Housatonic,' was one of 31 nuclear explosions in Operation Dominic.
The device was detonated about 12,100 feet (3,700 meters) above the Johnston Atoll in the Pacific Ocean and yielded a blast of 8.3 megatons -- more than 400 times as strong as either of the bombs dropped on Japan during World War II.
Far off from ground, nuclear blasts make fireballs that initially form a perfect orb. Yet the updraft soon mushrooms each explosion.
However, some of the most interesting blasts were filmed at a desert location now called the Nevada National Security Site.
In most cases, a metal tower was erected, held down with wires, and a nuclear weapon was placed on top. The structures raised bombs hundreds of feet off the ground.
Given the expense and importance of the tests, researchers filmed them from a variety of angles and distances.
Not all of the blasts went as planned. This one yielded about 80 times less energy than the bomb that exploded over Hiroshima.
'Rushmore' -- part of Operation Hardtack-2 in October 1958 -- blew up with a yield of only 188 tons' worth of TNT dynamite.
It was set off from a balloon that was tethered about 490 feet (150 meters) off the ground.
Smaller 'tactical' nuclear weapons -- which the American, Russian, and Pakistani militaries have developed but never used -- could have blasts like the one in this footage on a battlefield.
Analysing each film takes about 4 hours, Spriggs told Business Insider. To estimate a yield, he has to measure the blast's fast-moving shock wave and -- frame-by-frame -- compare it to the expansion of the bright inner fireball.
Operation Teapot's 'Turk' test blast was about 43 kilotons, or nearly three times greater than the Hiroshima blast. It was detonated 490 feet (150 meters) off the ground on March 7, 1955.
The jets that shoot out of the sphere at the beginning of this clip are called 'rope tricks,' since they are actually the wires that hold down the tower being vaporized.
When the blast's shock wave reaches the ground, it inflicts catastrophic damage and bounces upward and sideways. The fireball then follows to incinerate just about anything in its path.
After 1963, Russia and the US agreed to move nuclear weapons testing underground to prevent radioactive fallout, since it can increase rates of cancer.
Operation Plumbbob's detonation of 'Rainier' on September 19, 1957 yielded only 1.7 kilotons. However, it was the first nuclear explosion ever to be fully contained underground -- and leak no radioactive fallout into the air.
The shock wave could be detected around the world. At the lower left, you can see a giant boulder rolling down the hill at the Nevada National Security Site.
The test led the way for larger subterranean tests, especially after the Nuclear Test-Ban Treaty went into effect in August 1963.
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