Nikolai Kardashev graduated from the astronomical department of the faculty of mechanics and mathematics of Moscow State University in 1955. In 1959 Kardashev presented his Ph. D. thesis, that was performed at the Sternberg Astronomical Institute (SAI) under the supervision of I. S. Shklovsky. For his thesis he was awarded the degree of Doctor of Physics and Mathematics. After that he worked at the SAI in 1959-1967, from 1967 to 1990 at the Space Research Institute (IKI) of the Soviet Academy of Sciences. In 1990 Nikolai Kardashev organized Astro Space Center of Lebedev Physical Institute and until the last day remained its head. He was a full member of the Russian Academy of Sciences (1994), chairman of the Council for Astronomy of the Russian Academy of Sciences, member of the European Academy of Sciences, International Academy of Astronautics, American Astronomical Society, International Astronomical Union. Over the years, he was elected as a vice president of COSPAR and the IAU. N. S. Kardashev was twice awarded the USSR State Prize (1980, 1988). In 2011 he was awarded the Order of Honour, in 2012 he was awarded the Grotto Reber international medal for the development of radio astronomy. He was recognized as the Person of the Year in Russia in 2012, and in 2014 he was awarded the Demidov Prize. All of his awards and titles cannot be listed in this short obituary.
His whole life is an endless devotion to science. N. S. Kardashev predicted the possibility of observing the spectral line recombination in radio wavelength range. The recombination is formed upon transitions between the upper quantum levels of excited state of hydrogen, helium and other elements. He developed a theory for the evolution of the spectrum of synchrotron radiation from the cosmic radio sources. Even before the discovery of pulsars N. S. Kardashev predicted the presence of a neutron star in the Crab Nebula. The idea of the multiplicity of inhabited worlds has always excited him. He is the author of the classification of extraterrestrial civilizations, that is recognized around the world. In 1972-73 a search for extraterrestrial signals in the decimeter range of radio waves was performed under the leadership of N. S. Kardashev. In the first half of the 60s N. S. Kardashev proposed together with the colleagues the most important method of modern radio astronomy – very long baseline radio interferometry (VLBI). This method has been brilliantly implemented in global interferometric networks that have been successfully operating for more than half of a century and which solve both the most important fundamental and applied problems. A further development of this method was the Radioastron space-ground interferometer. N. S. Kardashev worked hard on this project for over three decades. Radioastron made it possible to obtain an angular resolution of several micro arcseconds, that is an unprecendent resolution in astronomy. The further development of Radioastron project is the Millimetron project, which Nikolay Semenovich Kardashev has been actively working on in the recent years. Until the last days, he remained a generator of bold scientific ideas. Together with his co-authors he worked on the development of multiverse theory with a system of wormholes.
The bright memory of this outstanding scientist will remain in our hearts, and his name in the history of science.
