Rocket engineers in the 1960s had their sights set on the Moon, and multistage rockets seemed to be the way to get there. In a multistage rocket, two or more rockets are mounted together one atop the other so that they can provide thrust at different stages in flight. The first rockets carry the others to a certain altitude and then drop off as their fuel is exhausted.
In the United States, the leading rocket scientist, Wernher von Braun, developed the Saturn V, which was 36 stories tall, could generate nine million pounds of thrust, and could launch a 150-ton payload into orbit around the Moon. Its bottom stage was so enormous that it had to be shipped by barge. Saturn V launched the Apollo missions, which ultimately landed men on the Moon in 1969.
The USSR's chief rocket designer, Sergei Korolev, was working on a rocket known as the N-1. It was a monstrous machine -- 310 feet from tip to tail and powered by thirty engines theoretically capable of developing 150 tons of thrust each. The N-1 was intended to launch cosmonauts to the Moon in a Soyuz spacecraft. But the Soviets were having trouble with the N-1, and, as NASA started to overtake them, they abandoned the goal of a manned mission to the Moon and turned their attention to the Proton rocket, an upgraded version of the World War II A-2 rocket, in order to launch the Salyut space station.
