This entry is part 5 of 10 in the series Nevada Theme Month

The Fastest Human-Made Object

“Many years later, when I was in Baikonur, the subject of Russia being the first to launch something into space came up. I did not raise my hand to add to the discussion, though I thought about doing so.”

— Robert Brownlee

What is the fastest object ever crafted by humans?

If you guessed some sort of spacecraft, you’re certainly correct. The current record holder for this distinction goes to the Parker Solar Probe, though its tale of velocity dominance is a bit of a buzzkill. Launched in 2018, Parker did not zip away from Earth at the fastest human-induced speed. Instead, it has reached an astounding 430,000 miles per hour (690,000 kilometers per hour) thanks to gravity assists from Venus. As it flies by our neighbor, it accelerates. This figure is 0.064% the speed of light, which is fast enough to go from New York to Tokyo in one minute!

On subsequent trips around the Sun, Parker will go even faster.

Letting Venus do all the work isn’t super flashy, though. Thankfully, the history of the record for the fastest human-made object is a little more Oppenheimer.

The initial atomic bomb tests transpired in New Mexico. By the 1950s, the U.S. government moved A-tests to the Nevada Test Site, making booms that could be seen from Las Vegas and producing very large craters. All the experimentation made for increasingly refined weapons but also created a big problem: nuclear fallout.

One potential solution to this issue was to quit traditional tests and move the explosions underground. Tasked with this new frontier was Robert Brownlee, during Operation Plumbbob. He directed a 500-foot borehole to be dug into the Nevada desert, in an attempt to restrict the aftermath of a nuclear detonation. Unfortunately, the yield on the bomb during the test known as Pascal-A overachieved, producing 50,000 times the anticipated power. Whoops. The result, in Brownlee’s words, was the “biggest damn Roman candle you ever saw!”

For Pascal-B, the researchers decided to add a 2,000-pound iron lid, despite Brownlee’s assertions that something of this size had no chance of hampering or surviving the blast. Still, with curiosity piqued, Brownlee et al aimed a camera with the ability to capture a frame every millisecond at the cap.

As predicted, the impediment stood no chance.

The cap was obliterated, but a manhole cover on top of it entered scientific lore. The camera caught the plate in exactly one frame, meaning it had exited the area in 0.001 seconds. When Brownlee calculated how fast it must have been moving, the lower end of possible values hit 60 kilometers per second!

Translated to American, this velocity equals nearly 135,000 miles per hour.

To put this speed into perspective, the rate at which an object must move to escape Earth’s gravity is approximately 25,000 miles per hour. The manhole cover’s speed was easily the fastest an object crafted by humans had reached to that point. Not until we could harness the power of the planets was this record eclipsed.

The tale of the accidental champion might have ended nearly as quickly as it started. Most scientists – Brownlee among them – believed the slab would have vaporized as it moved upward in the atmosphere, much like a meteor in reverse.

Months later, the Soviets sent Sputnik 1 into space, making the satellite the first human-made object to leave Earth.

Or was it?

Brownlee harbored some slight doubts about the vaporization of the manhole cover, at least as a thought experiment. The object had been accelerated to such a high speed that it might not have had enough time to burn up in the atmosphere. In other words, if it survived instant vaporization, it might have moved too quickly to suffer the fate of a meteor. If this scenario were correct, the satellite sophistication of Sputnik would have been replaced in the history books by an ignominious manhole cover.

Was the metal plate annihilated or did it shoot into outer space? The cover was never recovered, which seems to present evidence in absentia for both hypotheses! Most physicists continue to maintain a position of vaporization.

Or, just maybe, there’s a circular hunk of iron 80 billion miles from Earth, heading from its birthplace at the Nevada Test Site toward the deep cosmos.