NASA's Mercury and Gemini programs put the first Americans in space.

The Mercury spacecraft was smaller than a Volkswagon Beetle. It had one small window and no room to move around inside. An astronaut had to wedge himself inside for a flight, which lasted anywhere from 15 minutes to 34 hours.

The Mercury program proved that humans could survive in space. Scientists studied the effects of spaceflight on the human body. They examined the effects of high-gravity acceleration (from riding the rocket into space and re-entering through the atmosphere) and weightlessness. Alan Shepard was the first American to fly in space: on May 5, 1961, his spacecraft Freedom 7 was launched into a 15-minute flight by a Redstone rocket. Almost one year later, in February 1962, John Glenn became the first American to orbit the earth.

The Gemini program followed Mercury in the mid-1960s. Gemini astronauts walked in space, lived in space for up to two weeks, and docked with other spacecraft. They helped us learn much more about how people can function in space, paving the way for both the Apollo moon missions and space stations like Skylab and the International Space Station. Learn more about Mercury and Gemini at NASA's Space History Web site.

Mercury and Gemini photographs courtesy NASA