Creation of such unprecedented, even to modern measures, on-orbit research complex became possible due to comprehensive approach to modular construction of the Mir orbital station laid as far back as at its design stage. This approach was not a casual choice, it was the result of the 35-year operation experience on development and purpose use of manned orbital vehicles and stations, as well as heavy use of accumulated substantial experience in all lines of research and engineering activities in space. Many enterprises and organizations of the former USSR, institutions of the Russian Academy of Sciences and foreign participating countries have made a substantial contribution to this experience.