The Fastest Human-Made Object Is a Manhole Cover Shot Into Space

How could an iron manhole cover be the fastest human-made object ever launched?

I honestly pictured something akin to the exploding manhole covers that terrify NYC residents: Manhole Cover And Frame

The Fastest Human-Made Object Is a Manhole Cover Shot Into Space

It wasn't like that. This manhole cover was shot into space with a nuclear bomb.

Robert Brownlee, an astrophysicist who designed the nuclear test in question, told Insider the unbelievable story in 2016, before he died at the age of 94 in 2018.

Brownlee refuted the non-believers and asserted that yes, it likely was the fastest object that humankind ever launched.

Here's how Brownlee says history was made.

By 1962, the US was conducting every nuclear test underground.

The first one, nicknamed "Uncle," exploded beneath the Nevada Test Site on November 29, 1951.

Uncle was a code for "underground."

It was only buried 17 feet, but the top of the bomb's mushroom cloud exploded 11,500 feet into the sky.

Brownlee said he designed the Pascal-A test as the first that aimed to contain nuclear fallout. The bomb was placed at the bottom of a hollow column — 3 feet wide and 485 feet deep — with a 4-inch-thick iron cap on top.

The test was conducted on the night of July 26, 1957, so the explosion coming out of the column looked like a Roman candle.

Brownlee said the iron cap in Pascal-A exploded off the top of the tube "like a bat much hotter than hell."

Brownlee replicated the first experiment, but the column in Pascal-B was deeper at 500 feet. They also recorded the experiment with a camera that shot one frame per millisecond.

On August 27, 1957, the "manhole cover" cap flew off the column with the force of the nuclear explosion. The iron cover was only partially visible in one frame, Brownlee said.

When he used this information to find out how fast the cap was going, Brownlee calculated it was traveling at five times the escape velocity of the Earth — or about 125,000 miles per hour.

"The pressure at the top of that pipe was enormous," he told Insider in 2016. "The first thing that you get is a flash of light coming from the device at the bottom of the empty pipe, and that flash is tremendously hot. That flash that comes is more than 1 million times brighter than the sun. So for it to blow off was, if I may say so, inevitable."

"After I was in the business and did my own missile launches," he told Insider in 2016, "I realized that that piece of iron didn't have time to burn all the way up [in the atmosphere]."

Since it was going so fast, Brownlee said he thinks the cap likely didn't get caught in the Earth's orbit as a satellite like Sputnik and instead shot off into outer space.

Some people have doubted the incredible manhole cover story over the years. But Brownlee, with first-hand knowledge of the test, said he knows the truth.

"From my point," he told Insider in 2016, "it sure happened."

The Fastest Human-Made Object Is a Manhole Cover Shot Into Space

Aluminum Manhole Cover This story has been updated.