On Oct. 4, 1957, the Soviet Union launched Sputnik 1, the first satellite into an elliptical, low-Earth orbit. It was only 184lbs with a 23" diameter and managed to stay in orbit for 21 days before the battery powering the transmitter ran out. It burned up in the atmosphere three months later. This marked the beginning of what would be known as the "Space Race" between the Soviets and the U.S.
However, according to legend, America may have accidentally beaten the Soviets at launching something into space — a manhole cover.
In the summer of 1957, during Operation Plumbob, American scientists were testing the capabilities of nuclear explosions in all fashions at the Los Alamos Scientific Laboratory. They tested different alloys, various yield sizes, and, controversially, how troops react to exposure, but this story's all about using a nuclear explosion as a propellant.
Fun Fact: Many tourists came from Las Vegas to witness the nuclear blasts. Probably not the best idea. (Image via Wikimedia Commons)
When asked about the manhole cover, Dr. Robert Brownlee, the designer of the experiment, said that there was no way to account for all the variables at play and determine the fate of the steel cover. When pressed by a supervisor, he said that it must have reached six times the escape velocity of Earth (which is 11.2km/sec). A more modern estimate puts the speed of the steel cap at around 56 km/sec. For comparison, the speed of sound in air is 0.33 km/sec — or if you need a more veteran-friendly comparison, the muzzle velocity of an M4 is 0.9km/sec. The fastest man-made thing is the Helios 2, which travels 70.2km/sec.
There was no way to verify any of this, as the manhole cover was never found, but if the math was right and the manhole cover survived the extreme pressure and heat, Dr. Brownlee may have made it to space first, created the fastest object while in Earth's atmosphere, and the third-fastest object known to man.