Soyuz TM-20 was the 20th mission and the 17th long-duration expedition to Mir space station. The mission began on October 3, 1994, 22:42:30 UTC, launching Commander Alexander Viktorenko, Flight Engineer Yelena Kondakova and Research Cosmonaut Ulf Merbold into orbit. They docked with Mir two days later. During their stay there, cosmonauts performed two EVAs, carried out various scientific experiments. Station crew was visited by several Progress resupply spacecrafts, and welcomed aboard the Soyuz TM-21 crew. During this mission the first rendezvous maneuver of the Space Shuttle STS-63 with the Mir space station was performed.
The mission concluded with a safe landing back on Earth on March 22, 1995, 04:04:05 UTC.