Salyut programme(URSS)

The Salyut programme   was the first space station program undertaken by the Soviet Union, which consisted of a series of four crewed scientific research space stations and two crewed military reconnaissance space stations over a period of 15 years from 1971 to 1986. It was, on the one hand, designed to carry out long-term research into the problems of living in space and a variety of astronomical, biological and Earth-resources experiments, and on the other hand this civilian program was used as a cover for the highly secretive military Almaz stations, which flew as well under the Salyut designation.
Salyut 1, the first station in the program, became the first crewed space station in the history of mankind.
Salyut broke several other spaceflight records, including several mission duration records, the first ever orbital handover of a space station from one crew to another, and various spacewalk records. The Soyuz program was vital for evolving space station technology from basic, engineering development stage, single-docking port stations to complex, multi-ported long-term orbital outposts with impressive scientific capabilities, whose technological legacy continues to the present day. Ultimately, experience gained from the Salyut stations went on to pave the way for multimodular space stations such as Mir and the International Space Station, with each of those stations possessing a Salyut-derived core module at its heart.
Mir-2 (DOS- 8), the final spacecraft from the Salyut series, became one of the first modules of the ISS, and the first module of the ISS, Russian-made Zarya, relied heavily on technologies developed in the Salyut programme.