Back in 1945, Life magazine revealed to its readers how “U.S. Army technical experts came up with the astonishing fact that German scientists had seriously planned to build a ‘sun gun’.”
This, the magazine explained, would have been a gigantic orbital mirror that would “focus the sun’s rays to a scorching point on the earth’s surface.” The German army, readers were told, “hoped to use such a mirror to burn an enemy city or to boil part of an ocean.”
The idea had been originally proposed by the seminal rocket scientist, Hermann Oberth, in 1923. As late as 1957, he was still convinced that his space mirror would become a reality.
“My space mirror,” he wrote, “is like the hand mirrors that schoolboys use to flash circles of sunlight on the ceiling of their classroom. A sudden beam flashed on the teacher’s face may bring unpleasant reactions...I was a schoolteacher long enough to have collected certain data on the subject.”
Life magazine could only speculate on how the German space mirror could be built. Its editors and illustrator imagined it assembled from prefabricated sections. These would eventually form “a slightly concave disk one mile in diameter.” Life thought such a satellite should be built in a geosynchronous orbit. “The Germans,” the editors sniffed, “complicating the problem, planned to build their mirror at 5,100 miles.”
The Life version of the mirror would be a manned space stations, with 30-foot holes in which supply rockets could dock, hydroponic gardens to provide oxygen and solar powered generators for electric power. The entire surface of the mirror---front, back and edges---would be mirrored, “otherwise [the sun’s rays] would burn occupants of disk to death instantly.” Which might be a clue to how much Life's editors knew about outer space.
In reality the building of the mirror would begin with the launch of a single unmanned rocket. Once in orbit, it would unreel six long cables, each only 1/2 to 1 1/2 inches thick. Spinning the rocket on its axis would extend the cables radially.
more here: http://io9.com/how-germany-planned-to-fry-the-world-462891057