rigidity. They then used an electron gun to weld several of the girder's joints. This second EVA lasted five hours. Ferry flight back to Mir The crew removed 20 instruments with a total mass of 350 to 400 kg from Salyut 7 before returning to Mir. Mir maneuvered twice again between 24–25 June, raising its orbit slightly and moving closer to Salyut 7. On 25 June, Soyuz T-15 undocked from Salyut 7 to begin their 29-hour journey back to Mir, to which they returned on 25–26 June. On 3 July, Kizim surpassed Valeri Ryumin's record for time spent in space. On 6 July, he became the first human to have spent a full year in space. The crew spent their last 20 days on Mir conducting Earth observations. Meanwhile, between 19 and 22 August, engines on Kosmos 1686 boosted Salyut 7 to a record-high mean orbital altitude of 475 km to forestall reentry. Atmospheric drag took its toll, however, and the station reentered over South America 55 months later. Pieces of Salyut 7 and Kosmos 1686 were found in Argentina. Soyuz T-15 was the last mission to use the Soyuz-T spacecraft, due to its replacement by the Soyuz-TM. See also Soyuz T-13, a mission to manually dock to the crippled Salyut 7 space station, which used similar techniques practiced by the Soyuz T-15 crew in their approach to Mir. References Crewed Soyuz missions 1986 in spaceflight 1986 in the Soviet Union Mir Spacecraft launched in 1986 Spaceflight between space stations