The first American astronaut to orbit the planet Earth, John Glenn, died on December 8, 2016, at the age of 95. Although Glenn was being treated at the Ohio State Cancer Center, the exact cause of his death hasn’t been released by his family.

Glenn served as a combat pilot in World War II and Korea, flying 149 combat missions over the course of the two conflicts. After the war, Glenn became a test pilot, and upon hearing of a new manned space program, he signed up. Glenn was selected to be one of the seven astronauts that would become part of the Mercury Space Program, with the goal of putting an American in orbit. Following the sub-orbital flights performed by teammates Alan Shepard and Gus Grissom, Glenn would pilot the Mercury capsule Friendship 7 as the first American to complete a full orbit of the Earth, on February 20, 1962.

After leaving the space program in 1964, Glenn entered politics, serving as a senator representing Ohio from 1974 to 1999. In 1998, Glenn returned to space, serving as a Payload Specialist for the space shuttle Discovery on STS-95. At the time, Glenn was 77 years old, making him the eldest person in space. His participation in the mission offered researchers a unique opportunity, to study the effects of weightlessness on a person, with data collected from two points in the subject’s life, 36 years apart.

"Zero G, and I feel fine." ~ John Glenn, reacting to the weightlessness he experienced while piloting Friendship 7