As part of the final stages of World War II, the United States dropped an atomic bomb on Nagasaki, Japan in August 1945. Today, the location remains the largest city to undergo a nuclear attack.
This footage shows "the loading of the Fat Man bomb into the Bockscar plane on the island of Tinian," as Nuclear Secrecy Blog's Alex Wellerstein, a historian of science at the American Institute of Physics, wrote.
The bomb, an implosion-type bomb with a plutonium core, killed more than 70,000 people, according to Wellerstein.
He downloaded the video from the Los Alamos National Laboratory and added some of his own notes but no other editing. The scenes are haunting.
We broke out some screenshots, via The Aviationist. All the notes come straight from Wellerstein.
The hanger, where the U.S. stored the bomb, was 1,600 miles from Nagasaki. The Fat Man, a plutonium-centered implosion bomb, was over 10,000 pounds. But the nuclear core was only 13 pounds and about the size of an orange.
Soldiers working on the bomb didn't need protection from the small amount of radiation deep within the bomb. Notice the logos on the back of their shirts read: "FM" for "Fat Man," the name of the bomb.
Many soldiers even signed the bomb. For example, there was a stencil on the nose with "FM 1" and above someone wrote "JANCFU" — Joint Army Navy Civilian F*** Up.
Before transporting the bomb, the soldiers covered it with a tarp. Outside of the people in the assembly area, even the shape was still considered secret and would remain that way until 1960.
Scientists at Los Alamos calculated about a 20% failure rate for the Fat Man's design. And aside from the plutonium core, the bomb contained high levels of TNT for denotation. It had to be handled carefully.
A B-29 Superfortress named "Bockscar" — specifically designed for Project Silverplate — would transport the bomb. Most of the aircraft's weaponry and armor had been stripped away so it could hold more weight. (If the Bockscar crashed, the bomb would detonate.)
This shot shows the Bockscar seen from another bomber, likely The Great Artiste. The triangle and "N" on the aircraft's fin marked it as a normal member of the 444th Bombardment Group, instead of the atomic 509th Composite Group. That way, the Japanese couldn't identify which bombers carried which bombs.
A soldier named Charles Sweeney piloted the plane. Kokura, Japan was the original target, but heavy clouds obscured visibility and caused the plane to move on to Nagasaki.
The above image shows the sky immediately after detonation.
The infamous "mushroom cloud" appeared rapidly. The cloud of a 20 kiloton bomb, like Nagasaki, can reach heights of around 25,000 feet.
Only a few moments after detonating, the cloud head grew taller than the observing aircraft. Notice the "stem" and "head" hadn't combined yet either. The bomb was actually detonated about 1,650 above seal level to maximize the destructive blast.
Thick black smoke eventually obscured the ground, blocking the view.
Watch the full video: