WHY THE FASTEST OBJECT EVER CREATED BY HUMANS WAS A MANHOLE COVER

This story crops up on the internet every once in a while and I love it. Sometimes science is just plain weird.
  1. In 1957, the United States commenced "Operation Plumbbob," a nuclear weapons testing program.
    It took place in Nevada, and was the biggest in the nation's history.
  2. One of the tests, code named "Pascal-b," detonated a 0.3 kiloton nuclear weapon underground.
  3. A shaft leading up to the surface from the detonation chamber was capped by a welded steel plate that weighed approximately 2000 pounds.
    A "manhole cover," if you will
  4. The force of the explosion instantaneously accelerated the plate to somewhere around 148,000 mph. That's Mach 194, or approximately six times Earth's escape velocity
    It was caught in a single frame of a high-speed camera
  5. At that speed, the plate would have reached space (~100 km up) in about 1.5 seconds, months before Sputnik
    What probably actually happened is it was vaporized by the insane heat of accelerating past escape velocity at sea level
  6. Lead researcher for the test, Dr. Brownlee, said the plate went "like a bat out of hell"
  7. That's the story of how we made a manhole cover go faster than anything before or since, including Voyager 1 (which is currently in interstellar space) and New Horizons (the probe that took some lovely photos of Pluto this summer), way back in 1957.