The history of space flight usually begins with the Sputnik, the Soviet satellite launched on October 4, 1957.
It's widely regarded as the first man-made object to achieve Earth orbit, since history books usually keep silent about an earlier launch, carried out by a group of
American scientists. Those unsung geniuses managed to propel an object upwards with five times the minimum escape velocity needed to reach space.
The object in question was a mineshaft cover.
I am not making this up.
On August 27, 1957, astrophysicist Bob Brownlee and other Los Alamos scientists detonated an atom bomb at the bottom of a 500-foot, concrete-lined vertical tunnel
drilled in the Nevada desert.
The goal of the test, codenamed Pascal-B, was to see what would happen if a plutonium bomb was accidentally detonated. The expected yield was equivalent to a few tons of TNT.
A steel lid, 10 cm thick and weighing several hundred kilograms, was placed directly above the bomb; it was expected that it would be blown off, but nobody knew
exactly how fast.
It turned out that the yield of the Pascal-B was closer to 300 tons of TNT; when the explosion vaporized the concrete walls of the shaft, the lid rose on a column of
superheated gas and emerged at an unprecedented speed of 56 Km/sec, as confirmed by high-speed cameras and by some calculations made afterwards.
They never found it.
Sadly, even if the lid was travelling well faster than the required escape velocity of 11.2 Km/sec, it's highly unlikely that it managed to reach Earth orbit,
being as it is that manhole covers are not known for their aerodynamic properties. One can only dream of a passing alien spaceship grazed by a flying saucer
made of solid steel. Damn crazy Earthlings.
Sources:
http://www.radiochemistry.org/history/nuke_tests/plumbbob/
http://www.strangehorizons.org/2002/20021021/manhole.shtml
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