Soviet cosmonaut Alexei Leonov, the first person to walk in space, has died at the age of 85 at the Burdenko Military Hospital in Moscow. His death was announced Friday, Oct. 11, by Roscosmos, Russia’s space agency.

Born in 1934, Leonov became the eleventh Soviet cosmonaut and achieved major milestones of space exploration. During the Voskhod 2 mission, on March 18, 1965, he exited his capsule for 12 minutes, performing the first human spacewalk. Leonov barely survived the excursion, after a malfunction with his suit forced him to drop its pressure in order to make his way back into the capsule.

“His name is lettered in gold in the world’s space exploration history,” Roscosmos said in a statement.

In July 1975, Leonov commanded the Soyuz capsule, which set a standard of international cooperation in space when it docked for two days with NASA’s Apollo capsule.

“We need heroes like him,” says Garik Israelian, an astronomer at the Institute for Astrophysics in Tenerife, Spain, and founder of the Starmus International Festival, an international gathering that celebrates science and the arts. Israelian, a close friend of Leonov, says that Leonov’s experience on the Soyuz-Apollo mission shaped his life.

He recalls Leonov telling him, “Space is a place for freedom, not weapons. We should collaborate and work together.”

An artist as well as a cosmonaut, Leonov took colored pencils altered for zero gravity with him on Voskhod 2, and sketched an orbital sunrise, which is considered the first piece of art created in space. In collaboration with Starmus, Leonov helped to create the Stephen Hawking Medal for Science Communication, which recognizes the work of those helping to promote public awareness of science.

Israelian recalls Leonov creating a sketch of Hawking in his hotel room and presenting it to him. The form of the medal itself was inspired by Leonov’s drawing, his first spacewalk and the home-built electric guitar of Queen band member and astrophysicist Brian May. Winners include Elon Musk, Neil deGrasse Tyson, Hans Zimmer, Brian Eno, Buzz Aldrin and Jean-Michel Jarre.

Leonov was inducted into the International Air and Space Hall of Fame in San Diego in 2000. He was portrayed in the 2017 film, “Spacewalk,” which premiered at Starmus 4 in Trondheim, Norway. He and U.S. astronaut David Scott co-authored the dual autobiography, “Two Sides of the Moon: Our Story of the Cold War Space Race,” which explores the space race from both sides of the Iron Curtain.

A visitation will be held in Leonov’s honor in Moscow on Tuesday, Oct. 15.