This chapter discusses remote sensing in the visible EM spectrum, beginning with images and technology from the first remote-sensing satellites (the Corona spy satellites). Following the Corona illustration, the chapter resumes the progression of photons through the atmosphere and into a spacecraft that began in Chapter 2.
Immediately following World War II, the U.S. began to experiment with imaging from space, first with captured V2 rockets and later with various versions of the rockets being developed as part of the U.S. missile program. These early experiments showed that it was possible to image the earth from space. By the late 1950s, it was time to attempt earth imaging from an orbital system.
Corona was America’s first operational space-reconnaissance project. It was developed as a highly classified program under the joint management of the CIA and USAF, a relationship that evolved into the National Reconnaissance Office (NRO). For context, the first Soviet satellite, Sputnik, was launched on October 14, 1957, and Van Allen’s Explorer spacecraft flew on a Redstone rocket on January 31, 1958. President Eisenhower approved the Corona program in February 1958. This decision proved to be farsighted: when Francis Gary Powers was shot down in a U-2 on May 1, 1960, the President was forced to terminate reconnaissance flights over the Soviet Union.
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