Alexei Leonov

MOSCOW (AP) — Alexei Leonov, the legendary Soviet cosmonaut who became the first human to walk in space 54 years ago — and who nearly didn’t make it back into his space capsule — has died in Moscow at 85.

The Russian space agency Roscosmos made the announcement on its website Friday but gave no cause for his death. Leonov had health issues for several years, according to Russia media.

Showing just how much of a space pioneer Leonov was, NASA broke into its live televised coverage of a spacewalk by two Americans outside the International Space Station to report Leonov’s death.

“A tribute to Leonov as today is a spacewalk,” Mission Control in Houston said.

Leonov — described by the Russian Space Agency as Cosmonaut No. 11 — was an icon both in his country as well as in the U.S. He was such a legend that the late science fiction writer Arthur C. Clarke named a Soviet spaceship after him in his “2010” sequel to “2001: A Space Odyssey.”