The scientific spacecraft “Spectrum-Roentgen-Gamma” (Spektr-RG or SRG) is an X-ray observatory. SRG’s main scientific goal is to chart an unprecedented map of the Universe in X-rays on which all large clusters of galaxies will be marked. Spektr-RG is able to carry out an all-sky survey with outstanding sensitivity. One of the core questions to be answered by Spektr-RG is what was the evolution of galaxies.

On 13 July 2019, the second spacecraft of the Spektr series, Spektr-RG, lifted off from the Baikonur cosmodrome launchpad №81 at 12:30 UTC. It followed on from the Spektr-R satellite telescope successfully launched on 18 July 2011. The Spektr-RG astrophysics space observatory continued to open up new possibilities for exploring the Universe.

Spektr-RG is a Russian project carried out by the Lavochkin Scientific and Production Association (NPO Lavochkin) with the participation of Germany, aimed at creating an astrophysics space observatory designed to explore the entire high-energy X-ray Universe. NPO Lavochkin is a leading enterprise of the rocket and space industry, carrying out work on the design, manufacture, testing and complex development of key automatic spacecraft for fundamental scientific research. The enterprise contributed to the accumulation of a powerful production potential for the development of aircraft, automatic space complexes of scientific and practical use.

One of the core questions to be answered by Spektr-RG is what was the evolution of galaxies. Spektr-RG is expected to find about 100,000 massive clusters of galaxies. Furthermore, it will detect around three million supermassive black holes in active galactic nuclei (AGN), along with hundreds of thousands of stars with active coronae and accreting white dwarfs, tens of thousands of galaxies with active star formation.
The project involves the creation of a national high-energy astrophysics observatory, which will continue the sequence of Astron and Granat astrophysics satellites, also constructed by NPO Lavochkin. The apparatus is built on a modular principle, has good orientation and stabilization characteristics, and allows to observe almost the entire celestial sphere during the year.
The Russian astrophysics observatory Spektr-RG, equipped with two unique X-ray telescopes, circling the Sun-Earth L2 Lagrangian point in a halo orbit. Astrophysical studies are scheduled for 6.5 years, of which 4 years – all-sky survey, and 2.5 years – observations of selected objects and regions on the request of the world scientific community. The complex has already performed two all-sky surveys, thanks to which the best map of X-ray sources to date has been created. A total of eight all-sky surveys will be performed, and the map will be significantly expanded, deepened and refined. And this map will be used by scientists for at least several decades.
The Spektr-RG high-energy astrophysics space observatory was commissioned by the Roscosmos State Corporation and designed to explore the entire high-energy X-ray Universe. For these purposes, it was equipped with two unique X-ray telescopes: the eROSITA built by the Max Planck Institute for Extraterrestrial Physics (MPE) in Germany, and the ART-XC built by the Russian Space Research Institute (SRI RAS) and All-Russian Scientific Research Institute for Experimental Physics (Sarov). The two telescopes were integrated into the Navigator platform. All together forms the spacecraft.
The main developer of the space complex and spacecraft is NPO Lavochkin, the main scientific organization is the SRI RAS.
As for the telescopes, they are both similar and different. They operate similarly. Each telescope consists of seven identical Wolter-type mirror modules. Each module also has its own detector. But they differ in sensitivity range: the eROSITA operates in the softer range and the ART-XC – in the harder range. Thus, they complement each other, providing more valuable scientific results.

To date, the telescopes of the Spektr-RG observatory have carried out their third all-sky survey (out of eight planned). The Roskosmos Corporation facilities control the satellite: the deep space communication antennas daily receive scientific data and send commands to the satellite and its instruments, which are a million and a half kilometers away from Earth (four times farther than the Moon). The SRI RAS fellows process the scientific data on computers at the Project Data Center.
In 2021, the Spektr-RG observatory was awarded the Marcel Grossmann Award “for creating the unprecedented map of the Universe in X-rays, for the discovery of millions of previously unknown supermassive black holes at cosmological distances, for recording X-rays from tens of thousands of galaxy clusters of ‘dark energy’, and for the possibility of a detailed study of the growth of the large-scale structure of the Universe in an era dominated by ‘dark energy’”:
the Lavochkin Scientific and Production Association (part of the Roskosmos State Corporation) for creation of the spacecraft with X-ray telescopes of the Spektr-RG observatory, for organizing its launch into space, flight control and receiving data from the observatory for two years;
the Max Planck Institute for Extraterrestrial Physics (MPE, Germany) for the creation of the unique X-ray telescope eROSITA;
the Space Research Institute of the Russian Academy of Sciences for the development of the general concept and scientific program of the Spektr-RG astrophysics space observatory and the leading role in the creation of the X-ray telescope ART-XC.