the atmosphere. A high-speed camera, which took one frame per millisecond, was focused on the borehole because studying the velocity of the plate was deemed scientifically interesting. After the detonation, the plate appeared in only one frame, but this was enough to make an estimation of its speed. Dr. Brownlee joked the best estimate of the cover's speed from the photographic evidence was it was "going like a bat!". Brownlee estimated that the explosion, combined with the specific design of the shaft, could accelerate the plate to approximately six times Earth's escape velocity. In 2015 Dr. Brownlee said, "I have no idea what happened to the cap, but I always assumed that it was probably vaporized before it went into space." Later calculations made during 2019 (although the result cannot be confirmed) are strongly in favor of vaporization. List of tests See also Lists of nuclear disasters and radioactive incidents Totskoye nuclear exercise Notes References External links Video clips: Historic color footage of shot "Owens", during Operation Plumbbob Plumbbob page on the Nuclear Weapons Archive (also refers to manhole cover issue mentioned above). Explosions in 1957 Plumbbob Radiation health effects research 1957 in military history 1957 in Nevada 1957 in the environment