The Fastest Human-Created Object is a … What?

From 1976 until 2003, if you wanted to travel by airplane across the Atlantic, and you wanted to go quickly, the Concorde was perhaps your best option. It was the fastest commercial airplane — with a maximum speed of 1,354 miles per hour (2,179 km/h), passengers were zooming across the planet at nearly twice the speed of sound. In other words, that’s really fast.

But if you want to see something go faster, that’s not even close to the peak of what humans have created. Bullets typically max out at about 3,000 mph (5,000 km/h). Top American fighter jets can top that speed by 50%. The Space Shuttles — the retired spacecraft used by NASA from 1981 through 2011 — rocketed into space at a speed approaching 17,000 miles per hour (27,358 km/h) on their into orbit. After that, if you want to go faster, you need to be in outer space, free of the Earth’s gravity and the friction of our atmosphere.

With one exception. The fastest object we’ve ever created — that (probably) isn’t traveling through space — isn’t a bullet or a plane or a rocket ship.

It was a manhole cover.

In 1945, the United States began testing nuclear weapons as part of the Manhattan Project. The Manhattan Project came to a close a year or two later, but nuclear weapons testing continued for decades. From May through October of 1957, the government detonated 29 bombs in the Nevada desert as part of Operation Plumbbob, hoping to develop better weapons.

The 17th Operation Plumbbob test, titled Pascal-B, took place on August 27, 1957. Like many of the Plumbbob tests, Pascal-B and its predecessor, Pascal-A, were underground tests — the researchers dug a 500 foot (150 m) deep hole, dropped the bomb to the bottom, and blew it up. The Pascal-A explosion revealed a problem with such a tactic: as The Register explains, “the bomb yield was much greater than anticipated – 50,000 times greater, apparently. Fire shot hundreds of feet into the air from the mouth of the uncapped shaft.”

So for the B test, the research team did something different: they capped the shaft. A one ton (900 kg) iron lid — the manhole cover — was placed at the top of the shaft in hopes of keeping any flames underground. But it didn’t work that way.

When the bomb went off, pressure built in the chamber under the iron lid, and the lid couldn’t hold it back. Ultimately, the force of the bomb shot the manhole cover skyward, at incredible speeds. How fast? Well, we’re not entirely sure, because it was moving too quickly to accurately measure. But we can be rather certain that it was going faster than anything had gone before — and, space probes aside, faster than anything since.

Dr. Robert Brownlee was an astrophysicist working on Operation Plumbbob, and as he recounted in 2002, he was skeptical that the lid would stay on. So he and a colleague set up a high-speed camera and pointed it at the blast site. The camera was able to capture 1000 frames per second (or one per millisecond) — but the manhole cover only appeared in one frame. Brownlee did a bunch of math, taking into consideration the camera’s distance from the launch site, to calculate the manhole cover’s speed skyward. He estimated that the manhole cover was traveling at a speed of at least 125,000 miles per hour (200,000 km/h) — making it easily the fastest-moving object in Earth history.

Brownlee’s photo hasn’t been released by the government, so we can’t double check his math, but others involved with the experiment confirm that the manhole cover was shot into the air — and no one disputes Brownlee’s claims. But there’s one item still unsettled: the whereabouts of the manhole cover itself. Simply put, it’s never been found. Most likely, it vaporized on its path through the atmosphere, but that’s not certain. For an object to escape the Earth’s gravitational pull, it needs to travel at a speed of at least 25,000 mph (40,000 km/h), and the lid was going roughly six times that speed. It’s possible that the manhole cover made its way into space and is on its way to a galaxy far, far away right about now. If so, it has an honor beyond “world’s fastest object” — it also is the first thing to ever go into space. Sputnik, the satellite typically given that distinction, wasn’t launched until October 4, 1957, five weeks after Operation Plumbbob.

Bonus fact: The fastest object humanity has ever created is in space right now, and no, it’s not the manhole cover. In 2018, NASA launched the Parker Solar Probe to gather all sorts of cool data from the Sun. The probe uses the gravity of other planets to help it get to the Sun — basically, as it approaches a planet, the gravitational pull of those planets gives the probe a nice acceleration boost. In October 2023, as Yahoo reported, the Parker Solar Probe reached a speed of 394,736 miles per hour (635,266 km/h), “thanks to a previous gravity-assist flyby from Venus.” How fast is that? Yahoo continues: “the Parker Solar Probe’s speed would hypothetically allow an airplane to circumnavigate Earth about 15 times per hour, or skip between New York City and Los Angeles in barely 20 seconds.”

From the Archives: The Race to Determine the Fastest Man Alive: (a) They’re not nearly as fast as the manhole cover or the Parker Solar Probe and (b) the race never happened. 😢