This was the first expedition to the under-construction Mir space station and the final crew mission to the Salyut 7 station. It is the first time a single mission visited more that one space station. The crew became the first to dock to and enter Mir and spent 55 days unloading two back-to-back cargo missions and activating and checking on Mir's systems. Two months into their mission, the crew undocked from Mir and made a 29-hour flight to the Salyut 7 space station. The crew spent two months on Salyut 7, performed two spacewalks, and collected equipment and experiments from the station to take back to Mir. The crew undocked from Salyut 7 on June 25th for the 29-hour flight back to Mir. This was the final flight of the Soyuz T variant.