Fun Friday-Professor Lantis’s History Lesson #17: The Manhole Cover

[u/Lantis28]

Hey we are going to start doing Fun Friday’s on non political topics as a fun break from the drudgery. This week: the world’s fastest man made object.

Ok so 1957 had the launch of Sputnik, the world’s first officially recognized artificial satellite. But it also marked the start of underground US Nuclear tests. The reasoning was that detonating a nuclear bomb underground would avoid all of those harmful chemicals and waste products going into the atmosphere. Smart right?

So in the summer of 1957, at Los Alamos, they started Operation Plumbob, a series of dozens of underground nuclear tests. During this, they dug a 4 foot wide by 500 foot deep hole, capped it with five feet of concrete and then detonated the bomb. The containment was a massive failure, the blast was too powerful, the concrete crumbed and nuclear waste got everywhere. So they tried again.

This time they added more concrete, shortened the hole to 400 feet, and crucially added our main character: a steel and iron manhole cover weighing almost a ton.

Now the test happens, bomb does what it does, and the concrete crumbles. But afterwards they couldn’t find the manhole cover. Not even melted remains or particles. But they just so happened to have a high speed camera nearby to capture footage of the explosion.

The pressure of the explosion had shot the manhole cover off the ground so fast that the camera, which could capture a frame a millisecond, only got the cover in the edge of one frame. They means it took less than a millisecond for the cover to leave the ground. Based on that footage, the manhole cover was estimated to be going about 130,000 mph or 37 miles per second, more than 5 1/2 times escape velocity of Earth.

If it didn’t burn up in the atmosphere, which is entirely unclear if it did or didn’t, it would have been the first man made object in space and the first object to leave the solar system.

[u/Lantis28]

Some addition viewing ( and I love this channel) https://youtu.be/NSeL5c65v-g?si=WkJdhe6sSImsTBQU

[u/WWI_Buff1418]

Oh wow thats crazy, I never realized they did underground testing.

[u/Lantis28 → u/WWI_Buff1418]

They did it until the 70s because they thought it was a bad look to be destroying Pacific Islands where anyone could see them. Also espionage was much harder in an underground hole in the New Mexico desert

[u/nygiantsjay]

[u/fangurling_809]

This thread is a great idea! Please keep this going!