All Aboard
On May 9th, 1991, Sergei Krikalev launched on the Soviet Space Station Mir for a five-month mission. In January 1992 Krikalev was into his eighth month of the mission and had no idea when he was coming home.
Source: esa.int
Krikalev was a flight engineer. He arrived at the Mir station with the first British astronaut, Helen Sharman, and Anatoly Artsebarsky, who spent five months aboard Mir. Sharman was conducting experiments and spent eight days on Mir.