Soyuz 26 carried Salyut 6 EO-1, which was the first long-duration expedition to the Salyut 6 space station. The mission began on December 10, 1977, 01:18:40 UTC, launching Commander Yuri Romanenko and Flight Engineer Georgi Grechko into orbit. They docked with the station the next day. During their 96-day stay in orbit, crew performed the first Soviet spacewalk since 1969 with the purpose of inspecting one of the stations docking ports. They also performed Earth observation, carried out various experiments and tested new navigation system. EO-1 crew was visited by Soyuz 27 and Soyuz 28 crews; the first ever refueling of the station was performed by an uncrewed cargo ship Progress 1 during the mission. EO-1 crew swapped vehicles with the Soyuz 27 crew, which allowed for a longer stay in orbit. EO-1 crew returned in the Soyuz 27 spacecraft, landing safely back on Earth on March 16, 1978, 11:18:47 UTC.