Nearly 60 years after the US banned above-ground nuclear testing, top secret films that captured the mushroom cloud explosions have been declassified.
Scientist Greg Spriggs felt it was important to preserve the thousands of clips before it was too late, as they were on the brink of decomposing.
The five-year conservation project has so far been a success, and 64 films have been released to YouTube as an "initial set" with more to come.
But it's a race against time - there's still around 3500 films to scan and the process, which requires military review, will take even longer.
More than 200 atmospheric tests were completed from 1945 until 1963.