U.S. Navy test pilot Alan Shepard joined the astronaut program in 1959.
He became the first American and the second man in space on May 5, 1961, when he piloted the Mercury spacecraft Freedom 7 on a 490-kilometer (300-mile), 15-minute suborbital flight.
He would return to space nearly a decade later as an Apollo astronaut. 

The suit was snug-fitting and would pressurize the lower body to avoid blood pooling in the pilot’s legs. The suit was adapted from its original cockpit design to one that would integrate into a spacecraft, the Mercury capsule. Engineers added additional buckles and pulleys to keep the suit in place for that one minute of microgravity that Shepard would experience during his flight. They added restraints to the shoulders so that the astronaut’s arms would not float uncontrolled while weightless. The gloves of the suit also feature fingertip flashlights so that the astronaut could focus a beam of light on any given point in the cockpit. 

Shepard named the Mercury capsule he flew in "Freedom 7," the number signifying the seven Mercury astronauts; NASA called the mission Mercury-Redstone 3 (MR-3). 

NASA gave "Freedom 7" to the Smithsonian in October 1961, the first crewed spacecraft accessioned into the Smithsonian's collection. 

Yuri Gagarin was a young Soviet air force pilot when selected with 20 others for cosmonaut training in 1960. His historic single orbit around Earth on April 12, 1961, took only 108 minutes from ignition to landing. After Gagarin returned and the Soviet press released news of his flight, he became an international hero.

Yuri Gagarin and Alan Shepard may have been the first people in space, but they weren't the first living creatures. 

The Soviet Union launched the dog Laika into space in November 1957 and proved it was possible to maintain life in space for at least a limited amount of time. 

NASA launched a chimpanzee on a suborbital flight in January 1961.

Shepard was part of the the "Mercury Seven," the seven American astronauts who would participate in the first human spaceflight program in the United States, Project Mercury. The other members of the seven were: Walter M. "Wally" Schirra Jr., Donald K. "Deke" Slayton, John H. Glenn Jr., M. Scott Carpenter, Virgil I. "Gus" Grissom, and L. Gordon Cooper, Jr. 

The seven were selected from over 100 candidates who met the minimum standards set by NASA. The standards included: being a qualified jet pilot, a graduate of test pilot school, under 40, in excellent physical condition, and less than 5 feet 11 inches tall (to comfortably fit in the spacecraft). The candidates who met that criteria then went through physical, mental, and psychological testing as part of the selection process. 

John Glenn became perhaps the most famous of the Mercury Seven astronauts, when he became the first American to orbit the Earth. (Yuri Gagarin was also the first person to orbit the Earth during his historic 1961 flight.)

His service to his country did not begin or end there, however. A U.S. Marine Corps fighter pilot, Glenn was decorated veteran of two wars, a U.S. Senator for Ohio, and an astronaut again when he traveled into space for the second time in 1998. He still holds the record as the oldest person ever to fly in space. (He flew nine days, October 29 to November 7, 1998, in Discovery as a payload specialist. NASA assigned him to Space Shuttle mission STS-95, with the purpose of researching the effects of spaceflight on the aging body. )