Thereafter, however, the Soviet Union sent up Salyut 3 (June 1974-January 1975), 4 (December 1974-February 1977), and 5 (June 1976-August 1977). Salyut 6 (September 1977-July 1982) and 7 (April 1982- ) were visited by a large number of international crews, including Cuban, French, and Indian cosmonauts and the first woman to perform extravehicular activity, Svetlana Savitskaya, during the flight of Soyuz T12 on July 17-29, 1984. One of the most notable flights of the Salyut/Soyuz series occurred in 1984 when cosmonauts Leonid Kizim, Vladimir Solovyov, and Oleg Atkov, spent 237 days aboard the Salyut 7 before returning to earth, the longest space flight to that date. Salyut 7, now abandoned, remains in orbit.
The Mir space station, which the Soviets designed as a successor to the Salyut series, was launched on February 19, 1986. Described by the Soviets as the core of the first permanently staffed space station, it features six docking ports and can accommodate two cosmonauts. In 1987, Colonel Yuri Romanenko spent 326 days aboard Mir, the longest space flight then on record. On April 12, 1987, the Soviets succeeded in docking Mir with Kvant, an 18,000-kg (40,000-lb) astrophysics module. Carrying four X-ray telescopes, the Kvant was designed to link with Mir and observe a newly discovered supernova. X rays from the exploding star, blocked by the earth's atmosphere, cannot be detected from earth. In 1987-1988, Soviet cosmonauts Vladimir Titov and Musa Manarov, set a new record for time spent in space--366 days. On March 16, 1995, Norman Thagard, a NASA astronaut and physicist, became the first American to board a Russian space station when he began a three-month visit on Mir. Nearly 100 NASA members had been invited to watch the historic launch from mission control near Moscow.