Valery Polyakov, the Russian cosmonaut who set the record for the longest single stay in space, has died aged 80.
Polyakov spent 437 days between January 1994 and March 1995 on the Mir space station.
He orbited the Earth more than 7,000 times before returning.
Polyakov had trained as a physician and wanted to demonstrate that the human body could endure extended periods in space.
When landing, Polyakov declined to be carried out of the Soyuz capsule, as is common practice to allow readjustment to the pull of gravity.
Instead, he was helped out of the capsule, and he walked to a nearby transport vehicle himself.
He had previously spent eight months in space on a mission between August 1988 and April 1989.
Polyakov received several awards and medals for his service to the Soviet and Russian space programmes, including the titles Hero of the Soviet Union and Hero of the Russian Federation, as well as receiving the Order of Lenin.
His death was announced by Russia’s space agency on Monday.
“His research has helped prove that the human body is ready to travel not only to Earth’s orbit, but also into deep space,” Roscosmos said in a statement, according to The Moscow Times.
It did not state a cause of death.