50 years of spaceflight

On May 25, 1961, President Kennedy urged Congress to make sending a man to the moon a national priority.

"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth," he said. "No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish."

As the U.S. and U.S.S.R. dueled for supremacy in space, they were locked in an equally intense terrestrial competition in Europe. Cold War tensions ratcheted up even further in 1961, when the Soviet-backed government in East Germany began building the Berlin Wall.

Smithsonian National Air and Space Museum

Yuri Gagarin, whose single orbit around Earth on April 12, 1961, made the young Russian air force pilot took an international hero. Russia's success also gave new impetus to American plans for space.

A Russian stamp commemorating Gagarin's achievement.

Russia put two dogs, Belka and Strelka, into orbit in August 1960. They survived and later produced litters of puppies.

The NASA-trained chimpanzee Ham was sent on a suborbital flight in January 1961. He survived the flight and lived until 1983.

U.S. Navy test pilot Alan Shepard became the first American and the second man in space on May 5, 1961, during his 15-minute suborbital flight.

Mercury astronauts were recovered by U.S. military ships after splashing down in the ocean.

Alan Shepard trains in a Navy centrifuge, which was used to accustom astronauts to strong acceleration and deceleration.

NASA used a modified Redstone rocket to launch Alan Shepard into space from Cape Canaveral in 1961.

NASA used a modified U.S. Air Force Atlas ICBM to launch John Glenn - as well as the next three Mercury orbital flights.

A look at the inside of Shepard's Freedom 7 capsule.

This iconic image published in Life magazine of the first American astronauts, who became known as the "Mercury Seven."

op row, left to right: Alan Shepard, Gus Grissom, Gordon Cooper. Front row, left to right: Walter Schirra, Deke Slayton, John Glenn, Scott Carpenter.

President Kennedy and John Glenn inspect Friendship 7.

The silver-colored coating flight suit Alan Shepard wore was design to increase his visibility in case of an emergency rescue.

The spacesuit worn by Yuri Gagarin was similar to the one pictured here. It featured a pressure layer that formed a sealed environment which him breathe. Underneath, he wore thermal clothes to remain warm.

A 1:3 scale model of the Mercury capsule, which was used by NASA to fly two suborbital missions and four orbital missions between 1961 and 1963. It performed so well that relatively few modifications were required during the duration of the Mercury program.

Smithsonian National Air and Space Museum. Licensed by Norman Rockwell Licensing, Niles, IL

A 1965 painting by Norman Rockwell of astronauts John Young and Gus Grissom. This work is on display at the National Air and Space Museum's Mall building from May 28 to Oct. 9, 2011, as part of the NASA | Art: 50 Years of Exploration exhibition.