Left as a monument to such tests, the 152-foot-tall tower "sits on top of a shaft which was originally drilled to a depth of 1,600 feet...The nuclear device would have been attached to the bottom of the rack and kept cold by using dry ice -- hence the name 'Icecap.' Subzero-degree air from the dry ice would have chilled the nuclear device to minus-42 degrees, simulating the temperatures a missile system would encounter in space."
July 7, 2012 4:00 AM PDT
Photo by: Daniel Terdiman/CNET
| Caption by: Daniel Terdiman
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