Sergei Avdeyev

Sergei Vasilyevich Avdeyev was born on 1 January 1956 in Chapayevsk, in the Samara region of Russia. A physicist by training rather than a pilot, he graduated in 1979 from the Moscow Engineering Physics Institute as an engineer-physicist and went to work at NPO Energiya, the storied enterprise that built the Soviet Union's crewed spacecraft. There he spent nearly a decade developing spacecraft systems before being selected as a cosmonaut in 1987 as part of an Energia engineer group. He completed basic training in 1989 and, like many of his generation, would spend his entire flying career aboard a single outpost: the Mir space station.

Avdeyev flew three long-duration expeditions to Mir, all as flight engineer. His first, launched on Soyuz TM-15 on 27 July 1992, kept him in orbit for roughly 189 days before landing in February 1993. His second flight, aboard Soyuz TM-22 from 3 September 1995, ran about 179 days and hosted the European Space Agency's Euromir 95 research program, one of the collaborative projects that opened Mir to international science in the 1990s. His third and most extraordinary mission began on 13 August 1998 aboard Soyuz TM-28. Originally planned as a shorter stay, it stretched to roughly 380 days as crew rotations were reshuffled during Mir's uncertain final years, and he finally returned on 28 August 1999 aboard Soyuz TM-29. Across the three expeditions Avdeyev conducted ten spacewalks totaling about 42 hours, servicing and upgrading the aging station's exterior.

When he came home in 1999, Avdeyev had accumulated approximately 747 days in orbit — a cumulative time-in-space record that he held from 1999 until it passed to Sergei Krikalev in 2005, and which has since been surpassed by later cosmonauts. Because he spent so long traveling at orbital velocity, he is sometimes cited as one of humanity's greatest 'time travelers': relativistic time dilation left him aged a small fraction of a second younger than he would have been on the ground. Honored as a Hero of the Russian Federation and later a recipient of the French Legion of Honour, Avdeyev retired from the cosmonaut corps in 2003. A lifelong amateur radio operator, he remains a respected figure in the history of long-duration spaceflight, remembered above all for proving how far the human body could be pushed in the weightless environment of Mir.