Valery Polyakov, the Russian cosmonaut who set the record for the longest single stay in space, has died at age 80, Russia’s space agency announced Monday.

Polyakov’s record of 437 days in space began on Jan. 8, 1994, when he and two others blasted off on a two-day flight to the Mir space station Mir, operated by the Soviet Union and later by Russia. While aboard Mir, he orbited the Earth more than 7,000 times, before returning on March 22, 1995.

Upon landing, Polyakov declined to be carried out of the Soyuz capsule, as is common practice to allow readjustment to the pull of