Mir EO-2 (also called Mir Principal Expedition 2) was the second long duration expedition to the Soviet space station Mir, and it lasted from February to December 1987. The mission was divided into two parts (sometimes called (a) and (b)), the division occurring when one of the two crew members, Aleksandr Laveykin, was replaced part way through the mission by Aleksandr Aleksandrov. Laveykin was replaced because ground-based doctors had diagnosed him with minor heart problems. Background The core module or Mir had been launched into orbit on 19 February 1986. It had been visited twice by the crew of Soyuz T-15, between March and July 1986, who transferred equipment from the previous Soviet space station Salyut 7. Prior to the arrival of EO-2, Mir was also visited by three Progress spacecraft, numbered 25, 26, and 27, as well as an unmanned Soyuz-TM spacecraft, designated TM-1. From July 1986 to the arrival of EO-2 in February, Mir remained unmanned. During this time an associated relay satellite ceased operation, and computers on Mir were malfunctioning. Progress 27 docked with the station on 18 January, and was still there when the EO-2 crew arrived. On 26 January, the Progress spacecraft boosted the station's mean altitude by 16 km to 345 km. Crew The crew from February to July 1987, consisted of Commander Yuri Romanenko, and Flight Engineer Aleksandr Laveykin. From July to December 1987 the crew consisted of Romanenko and Aleksandr Aleksandrov. EO-2 was originally planned to consist of Aleksandr Serebrov and Vladimir Titov, but shortly before launch of Soyuz TM-2 to start the expedition, the crew was changed to Romanenko and Laveykin, possibly due to illness. Titov and Serebrov were listed as the backup crew for the mission. Mission highlights The launch of Romanenko and Laveykin aboard TM-2 was broadcast live on TV; it was a night launch which occurred at about 1:30am local time. It was the first manned launch of the new Soyuz-TM spacecraft. Kvant docking On 30 March 1987, the module Kvant-1 was launched; it was the second module of the space station Mir, and would add 40 m3 of pressurized volume to Mir, bringing the total to about 130 m3. Attached to Kvant-1 was a Functional Service Module (FSM), which contained propellants, and was used to direct the module to Mir. At launch, the Kvant module had a mass of 11 tonnes, and the FSM had a mass