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The first American astronaut to orbit Earth, John Glenn passed away yesterday in Ohio. But he leaves an admirable legacy.

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Olivia: John Glenn died yesterday, in a hospital in Ohio. He was 95. Glenn was the first American to orbit Earth, which showed that the US was a serious contender in the space race and kickstarted a series of other missions to orbit.

His flight helped identify and solve a lot of challenges when it came to sending humans to orbit, and a lot of his success as an astronaut came from his ability to keep calm in a crisis. Glenn was born in Cambridge, Ohio, in 1921. He studied engineering for two years at Muskingum College, earning his private pilot’s license in the process, then dropped out after the attack on Pearl Harbor to enlist in the military.

He ended up in the Marines, and was a fighter pilot during both World War II and the Korean War, flying a total of 149 combat missions. After the war, he became a test pilot, which eventually led him to NASA, which was looking for test pilots to become astronauts. Out of more than 500 applicants, Glenn was one of 7 people chosen for the first group of astronaut recruits in 1959.

He made history with his first spaceflight on February 20, 1962, when he became the first American to orbit Earth. But it wasn’t a simple flight. Originally, the mission, called Mercury-Atlas 6, wasn’t even supposed to launch in February. It was scheduled for January 16, then delayed multiple times because of things like the weather and problems with the fuel tanks. Finally, on February 20, Glenn’s spacecraft, called Friendship 7, launched for real.

His first pass around the Earth went great. He even noticed that people in Perth, Australia, had turned on their lights for him to show their support, and asked mission control to thank them for him. But then things started to get more complicated.

First, there was a problem with the system that was supposed to control the spacecraft’s orientation in space, so for most of the flight Glenn had to use manual controls instead. Even though the manual controls had some issues too, he was able to keep control of Friendship 7, so the mission continued. Then, NASA mission controllers started getting some weird readings that said that the heat shield on Glenn’s spacecraft wasn’t attached properly.

The heat shield was supposed to protect the spacecraft from overheating as it re-entered the Earth’s atmosphere, so if it came loose, that would have meant a fiery, fatal end to the mission. If there was a problem, the best way to keep the heat shield attached involved the rockets that were used to slow down Friendship 7 during reentry.

Normally, these rockets would be jettisoned to keep the craft as light as possible, but they were strapped on in a way that helped secure the heat shield. So Glenn was told not to jettison them in the hope that it would help keep the heat shield on, and otherwise hope for the best.

In the end, Glenn landed safely, and it turned out that the heat shield was never actually in any danger of coming off — it was the sensor that was broken. After he landed, Glenn was given a standard questionnaire about the mission, which included a question about whether there had been any unusual activity. His answer? “No. Just a normal day in space.”

In 1965, Glenn retired from the Marines and went into politics. He served as senator of Ohio from 1974 to 1999. But in 1998, he broke another record: he became the oldest person to fly in space, when he spent just over a week in orbit on the Space Shuttle Discovery at the age of 77.

It was 36 years after his first spaceflight, and this time, things went a lot more smoothly. NASA used this mission to test how spaceflight affects older people, by monitoring Glenn’s health before, during, and after his flight. He was also part of some of the other experiments on that mission, like one that took readings while he slept.

It’s hard to quantify the impact that Glenn had on Americans and the world, but one thing’s for sure: his first flight changed history forever. And along the way, he showed that even when things go wrong, keeping your cool can help you make it through. So thanks for everything, John Glenn. We’ll leave the lights on for you.

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