Gagarin's flight came at a time when the United States and the Soviet Union were competing for technological supremacy in space. The Soviet Union had already sent the first artificial satellite, called Sputnik, into space in October 1957.
Before Gagarin's mission, the Soviets sent a test flight into space using a prototype of the Vostok spacecraft. During this flight, they sent a life-size dummy called Ivan Ivanovich and a dog named Zvezdochka into space. After the test flight, the Soviet's considered the vessel fit to take a human into space. [Infographic: How the First Human Spaceflight Worked]
Becoming a legendary astronaut
The third of four children, Yuri Alekseyevich Gagarin was born on March 9, 1934, in a small village a hundred miles from Moscow. As a teenager, Gagarin witnessed a Russian Yak fighter plane make an emergency landing near his home. When offered a chance years later to join a flying club, he eagerly accepted, making his first solo flight in 1955. Only a few years later, he submitted his request to be considered as a cosmonaut. [Photos: Yuri Gagarin & 50 Years of Human Spaceflight]
More than 200 Russian Air Force fighter pilots were selected as cosmonaut candidates. Such pilots were considered optimal because they had exposure to the forces of acceleration and the ejection process, as well as experience with high-stress situations. Gagarin, a 27-year-old senior lieutenant at the time, was among the pilots selected.
On April 12, 1961, at 9:07 a.m. Moscow time, the Vostok 1 spacecraft blasted off from the Soviets' launch site. Because no one was certain how weightlessness would affect a pilot, the spherical capsule had little in the way of onboard controls; the work was done either automatically or from the ground. If an emergency arose, Gagarin was supposed to receive an override code that would allow him to take manual control, but Sergei Korolev, chief designer of the Soviet space program, disregarded protocol and gave the code to the pilot prior to the flight.
Over the course of 108 minutes, Vostok 1 traveled around the Earth once, reaching a maximum height of 203 miles (327 kilometers). The spacecraft carried 10 days' worth of provisions in case the engines failed and Gagarin was required to wait for the orbit to naturally decay. But the supplies were unnecessary. Gagarin re-entered Earth's atmosphere, managing to maintain consciousness as he experienced forces up to eight times the pull of gravity during his descent.
Vostok 1 had no engines to slow its re-entry and no way to land safely. About 4 miles (7 km) up, Gagarin ejected from the spacecraft and parachuted to Earth. In order for the mission to be counted as an official spaceflight, the Fédération Aéronautique Internationale (FAI), the governing body for aerospace records, had determined that the pilot must land with the spacecraft. Soviet leaders indicated that Gagarin had touched down with the Vostok 1, and they did not reveal that he had ejected until 1971. Regardless, Gagarin still set the record as the first person to leave Earth's orbit and travel into space. [Milestones in Human Spaceflight: Pictures]
Upon his return to Earth, Gagarin was an international hero. A cheering crowd of hundreds of thousands of people greeted him in Red Square, a public plaza in Moscow. A national treasure, Gagarin traveled around the world to celebrate the historic Soviet achievement.
When he returned home, Gagarin became a deputy of the Supreme Soviet of the Soviet Union (the highest legislative body in the Soviet Union) and was appointed commander of the Cosmonauts' Detachment. Because the Soviets did not want to risk losing such an important public figure, they were hesitant about allowing Gagarin to return to space. He continued to make test flights for the Air Force, however.
On March 27, 1968, Gagarin was killed (along with another pilot) while test-piloting a MiG-15, a jet fighter aircraft. He was survived by his wife, Valentina Ivanovna Goryacheva, and two daughters.
NASA's Apollo 11, the first mission to put people on the moon, landed in July 1969, and the crew left behind a commemorative medallion bearing Gagarin's name. They also left medallions for other astronauts who lost their lives in space or while preparing for spaceflight.
Over time, the U.S. and the Soviet Union began working together in their spaceflight endeavors. The first joint U.S.-Soviet spaceflight was in 1975, called Apollo-Soyuz. Following that, NASA sent several space shuttle astronauts to Soviet/Russian space station Mir after the fall of the Soviet Union in 1991. The shuttle-Mir collaboration paved the way for NASA and the Russian space agency (Roscosmos) to become major partners in the International Space Station program, which first launched modules in 1998 and continues research today.
Gagarin's importance in the Russian space program continues. Crews using the Soyuz spacecraft participate in a number of prelaunch traditions prior to climbing on to the spacecraft — such as urinating on the launch bus tires — to follow in the footsteps of Gagarin's historic flight. Beyond that, Gagarin is often held up as an example of character and heroism to younger children in Russia.
The 60th anniversary of Gagarin's flight will be in 2021. The space community also commemorates Gagarin's achievement every year with Yuri's Night, a celebration that takes place on his launch date of April 12. Yuri's Night was founded in 2001 and attracts thousands of celebrants each year.
This article was updated on Oct. 12, 2018 by Space.com Contributor, Elizabeth Howell.
Editor's Note: This article was updated on Oct. 15, 2018 at 10:08 a.m. EDT to reflect a correction. The 60th anniversary of Gagarin's flight will be in 2021.