Complex sentence: The Corona Program, conducted by the U.S. Air Force, involved the launching of satellites from the 50's through the 70's to take photographs to assess how rapidly the Soviet Union was producing long-range bombers and ballistic missiles.
Split into simpler sentences: The Corona Program, conducted by the U.S. Air Force, involved the launching of satellites from the 1950s through the 1970s. They were to take photographs to assess how rapidly the Soviet Union was producing long-range bombers and ballistic missiles.