Armstrong and Aldrin would, of course, go on to greater fame with the Apollo program—the series of missions that would finally take humans to the surface of the Moon. Apollo had the most complex set of objectives. Engineers had to design and build three separate spacecraft components that together made up the Apollo spacecraft. The service module contained life-support systems, power sources, and fuel for in-flight maneuvering. The conical command module would be the only part of the craft to return to Earth. The lunar module would ferry two members of the three-man crew to the lunar surface and then return them to dock with the combined service and command modules. Another major task was to develop new tough but lightweight materials for the lunar module and for spacesuits that would protect the astronauts from extremes of heat and cold. And then there was what has often seemed the most impossible challenge of all. Flight engineers had to perfect a guidance system that would not only take the spacecraft across a quarter of a million miles to the Moon but also bring it back to reenter Earth's atmosphere at an extremely precise angle that left very little room for error (roughly six and half degrees, give or take half a degree). If the angle was too steep, the capsule would burn up in the atmosphere, too shallow and it would glance off the atmosphere like a stone skimming the surface of a pond and hurtle into space with no possibility of a second chance.
Launching all that hardware—40 tons of payload—called for a rocket of unprecedented thrust. Von Braun and his rocket team again rose to the challenge, building the massive Saturn V, the largest rocket ever created. More than 360 feet long and weighing some 3,000 tons, it generated 7.5 million pounds of thrust and propelled all the Apollo craft on their way without a hitch. On July 16, 1969, a Saturn V launched Apollo 11 into space. Four days later, on July 20, Neil Armstrong and Buzz Aldrin became the first humans to set foot on the Moon, thus meeting Kennedy's challenge and winning the space race. After the tragic loss of astronauts Virgil I. (Gus) Grissom, Edward H. White, and Roger B. Chaffee during a launchpad test for Apollo 1, the rest of the Apollo program was a spectacular success. Even the aborted Apollo 13 mission proved how resourceful both the astronauts in space and the engineers on the ground could be in dealing with a potentially deadly catastrophe—an explosion aboard the service module. But with the space race won and with increasing cost concerns as well as a desire to develop other space programs, the Moon missions came to an end in 1972.