John Glenn died on Thursday in Columbus, Ohio, at 95. He was one of the "Original Seven" also known as the "Mercury Seven", who were the first cohort of Nasa astronauts.
They were in many ways an experiment in whether human space flight was possible. Glenn was considered one of the definitive American national heroes.
Although he didn't think of himself as a hero, the rest of America did.
President Barack Obama said his space missions had lifted the hopes of a nation. "John always had the right stuff, inspiring generations of scientists, engineers and astronauts who will take us to Mars and beyond – not just to visit, but to stay."
Here are some of the moments that defined his career.
He was the first American to orbit the Earth
In February 1962, Glenn blasted off from Florida at 9:47am in Friendship 7, a tiny capsule attached to an Atlas rocket. He orbited the Earth three times before landing again safely.
He wasn't the first person to orbit the Earth – the year before the Russian astronaut Yuri Gagarin achieved that feat. Although two other Americans had completed sub-orbital flights, skimming the top of the atmosphere, Glenn was the first American to make a true orbit of the Earth in space.
He was dedicated – he even made himself shorter so he could go to space
Glenn's close friend Tom Miller, a retired Marine general, says that Glenn took every measure possible to ensure that he met the requirements for potential Nasa stronauts. He would even pile up heavy books on top of his head to try to compress his spine to meet the 5ft 11in maximum height for an astronaut, according to the New York Times. "He wasn't going to miss a trick," Miller says. "He'd be sitting down reading with a big bunch of books sitting on his head."
He became the oldest man in space
At 77, Glenn became the oldest person to go into space, when he went on a 1998 Space Shuttle Discovery mission as a payload specialist. The research mission lasted nine days.
While aboard the mission, Glenn was the subject of ageing experiments. Measurements were made to record how his body responded in the low-gravity environment on the shuttle.
The shuttle orbited the earth 134 times during the mission, travelling a total of 3.6 million miles.
He fought in the Second World War
He joined the Naval Aviation Cadet Program in March 1942, a few months after the attack on Pearl Harbor at the end of the previous year. He joined the Marines in 1943, becoming a fighter pilot. He flew on 59 combat missions during the Second World War and earned two Distinguished Flying Crosses among other awards.
He ran for president in 1984
Glenn served for 24 years as US Senator for Ohio between 1975 and 1999. In 1984 he ran for the Democratic presidential nomination in 1984, losing to former US Vice-President Walter Mondale from Minnesota, who in turn lost the presidential race to Ronald Reagan.