After the fall of Nazi Germany at the end of World War II, the United States and the Soviet Union emerged as superpowers, each striving for primacy on a global scale. As rocket technology improved and spaceflight seemed possible, the dueling forces also set their sights on reaching and controlling space. Headlines of the 1950s and 1960s seemed to indicate that the Soviet Union was light-years ahead of the U.S. throughout much of the space race. But behind the scenes, a very different story was unfolding. Recently released documents reveal secret military plans, cover-ups, and covert spy missions that were part of humankind's ambitious journey into orbit and beyond. In this time line, explore the Cold War's secret space race.—Rima Chaddha