In late 1942, President Franklin Roosevelt and the United States government developed a top-secret plan. The goal: to develop atomic bombs -- and beat Nazi Germany in doing so. The code name: The Manhattan Project

View of the atomic fireball following the test detonation of the first nuclear bomb, the Trinity test, held at the White Sands Proving Ground, New Mexico,July 16, 1945.

Operation Greenhouse, 1951: High ranking military personnel sit in rows of deck chairs, wearing goggles, while illuminated by the flare of an atomic detonation at the Atomic Energy Commission's Pacific Proving Ground during Operation Greenhouse, 1951.

Manhattan Project leaders, including Robert Oppenheimer (white hat) and Gen. Leslie Groves (center), inspect the ruins of the tower from which the first atomic bomb test was conducted, July 16, 1945, in New Mexico.

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Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons (hydrogen bombs). Conducted at the new Pacific Proving Ground, all of the devices were mounted in large steel towers, to simulate air bursts. This series of nuclear weapons tests were preceded by Operation Ranger and succeeded by Operation Buster-Jangle.

Operation Greenhouse represented new and aggressive designs for nuclear weapons. The main idea was to reduce the size, weight, and most importantly, reduce the amount of fissile material necessary for nuclear weapons, while increasing the destructive power. With the Soviet Union's first nuclear test just a year and half earlier, the United States had begun stockpiling the new designs before they were actually proven. Thus the success of Operation Greenhouse was vital before the development of thermonuclear weapons could continue.