John Glenn was the third American to be launched into space and the first American to orbit Earth. Two Soviet cosmonauts had orbited Earth before him.
On 20 February 1962, NASA launched Friendship 7 and the first American astronaut who would orbit the Earth.
The Soviets achieved the first manned earth orbit on 12 April 1961, when Yuri A. Gagarin completed a one-orbit flight aboard the Vostok 1. Vostok 2 carried cosmonaut Gherman Titov into orbit for a full day on 06 August 1961.
The space race between the Soviet Union and the United States “was an outgrowth of the mid-20th-century Cold War.”
Glenn circled the globe three times in a flight lasting 4:55:23; he splashed down safely in the Atlantic Ocean approximately 800 miles southeast of Bermuda.
IBM computers calculated the path of the spacecraft to assist flight controllers with the “go, no go” decision. However, as the movie Hidden Figures spotlighted, Glenn famously said: “Get the girl to check the numbers.”
This changed Katherine Johnson’s role in history:
A “human computer” assigned to NASA’s Flight Research Division at Langley Research Center in Hampton, Virginia, Johnson was the African-American, then-44-year-old “girl” who was the subject of the astronaut’s directive. As such, she set about double checking the trajectory calculated by her electronic counterpart: room-size IBM 7090 computers at Goddard Space Flight Center in Greenbelt, Maryland.
“If she says the numbers are good, I am ready to go,” Glenn said, according to Margot Lee Shetterly in her book Hidden Figures which served as the basis for the 20th Century Fox movie by the same name.
She did. They launched. The rest is history.