There is a story told that the first manmade object to achieve escape velocity, was a [man hole style cover][1], over an exhaust vent, from an underground nuclear bomb test. However, they quote this on the website. > But the assumption that it might have escaped from Earth is > implausible (Dr. Brownlee's discretion in making a priority claim is > well advised). Leaving aside whether such an extremely hypersonic > unaerodynamic object could even survive passage through the lower > atmosphere, it appears impossible for it to retain much of its initial > velocity while passing through the atmosphere. A ground launched > hypersonic projectile has the same problem with maintaining its > velocity that an incoming meteor has. According to the American Meteor > Society Fireball and Meteor FAQ meteors weighing less than 8 tonnes > retain none of their cosmic velocity when passing through the > atmosphere, they simply end up as a falling rock. Only objects > weighing many times this mass retain a significant fraction of their > velocity. [1]: http://nuclearweaponarchive.org/Usa/Tests/Plumbob.html#PascalB