Ungrounded

Story is real enough. Dr. Karl recounts this same event in one of his "Great moments in science" books. According to Dr. Karl it was in fact the first man made object with sufficent escape velocity to be launched into deep space. A quick check (Google) tonight shows that reportedly at least one scientist directly involved has doubts:- http://io9.gizmodo.com/no-a-nuclear-explosion-did-not-launch-a-manhole-cover-1715340946 Have not researched any further. PS. Better link. Closer to the source:- http://nuclearweaponarchive.org/Usa/Tests/Brownlee.html