Artist's impression of the deployed Spektr-RG
Mission typeX-ray astronomy[1]
OperatorRussian Space Research Institute, German Aerospace Center
COSPAR ID2019-040A Edit this at Wikidata
SATCAT no.44432
Mission durationPlanned: 6.5 years[1]
Elapsed: 4 years, 6 months, 12 days
Spacecraft properties
ManufacturerNPO Lavochkin, Max Planck Institute for Extraterrestrial Physics
Launch mass2,712 kg (5,979 lb)[1]
Payload mass1,210 kg (2,670 lb)[1]
Power1.8 kW
Start of mission
Launch date13 July 2019, 12:31 (2019-07-13UTC12:31) UTC[1][3]
Launch siteBaikonur Site 81/24
Orbital parameters
Reference systemSun–Earth L2
RegimeHalo orbit
Main telescope
TypeeROSITA: Wolter
Spektr program

Spektr-RG (Russian: Спектр-РГ, Spectrum + Röntgen + Gamma; also called Spectrum-X-Gamma, SRG, SXG) is a Russian–German high-energy astrophysics space observatory which was launched on 13 July 2019.[4] It follows on from the Spektr-R satellite telescope launched in 2011.[5]


The original idea for this X-ray observatory satellite orbiting above Earth's atmosphere, which filters X-rays, was first proposed in the 1980s by Rashid Sunyaev of the Space Research Institute of the USSR Academy of Sciences. Twenty institutions from twelve countries came together to design a large observatory with five telescopes. However, after the collapse of the Soviet Union, the mission was abandoned due to cost-cutting from the Russian space program Roscosmos. The project was resurrected in 2003 with a scaled-down design.[6]


eROSITA overview animation from the German Aerospace Center showing the Spektr-RG mission profile

The primary instrument of the mission is eROSITA, built by the Max Planck Institute for Extraterrestrial Physics (MPE) in Germany. It is designed to conduct a seven-year X-ray survey,[7] the first in the medium X-ray band less than 10 keV energies, and the first to map an estimated 100,000 galaxy clusters.[8] This survey may detect new clusters of galaxies and active galactic nuclei. The second instrument, ART-XC, is a Russian high-energy X-ray telescope capable of detecting supermassive black holes.[8]


The Spektr-RG mission concept was published in 2005.[9] Construction was finished in 2016, and by mid-2018 it was under integration and testing. It was scheduled to be launched in June 2019 but was delayed to 12 July, before the flight was postponed at the last moment. It launched the next day, 13 July 2019, from Baikonur Site 81/24.[1] The observatory was integrated into a Navigator satellite bus,[10] produced by NPO Lavochkin.[11]

Mission profile and orbit

The spacecraft entered an orbit around the Sun, circling the Sun-Earth L2 Lagrangian point in a halo orbit, about 1.5 million kilometres away from Earth. Cruise to that location took three months, during which the two telescopes were checked out and calibrated. The next four years were planned to be spent performing eight all-sky surveys. As a goal, the three years after that are planned for observations of selected galaxy clusters and AGNs (Active Galactic Nuclei).[12]

On Monday 21 October 2019, Spektr-RG completed a 100-day cruise to L2-point. On 17 October 2019, the main eROSITA instrument achieved first light.[13] The first light image of ART-XC was taken on July 30, 2019.[14]

The operations of eROSITA were suspended on 26 February 2022 after the Russian invasion into Ukraine upon request from Germany. At the time, eROSITA had completed four of its planned eight full-sky surveys.[15]

In March 2022, Russia said they turned off one of the two telescopes aboard Spektr-RG (presumably eROSITA) as a response to the German reaction to the Russian invasion of Ukraine.[16] In June, the head of Roscosmos threatened to unilaterally seize control of the German telescope, citing German officials' "pro-fascist views".[17]


Spektr-RG instruments. eROSITA is the larger mirrors on the bottom left and ART-XC is the smaller mirrors on the top right.
Instruments on the Spektr-RG observatory
Organisation MPE IKI / VNIIEF
Telescope type Wolter Wolter
Wavelength X-ray X-ray
Mass 810 kg 350 kg
Sensitivity range 0.3–10 keV 4–30 keV
Field of view 1 degree 30 arcminutes
Angular resolution 15 arcseconds 45 arcseconds
Sensor area 2,400 cm2 at 1 keV 450 cm2 at 8 keV

Optical mission support

Spektr-RG on a 2020 stamp of Russia



See also


  1. ^ a b c d e f g Zak, Anatoly (16 April 2016). "Spektr-RG to expand horizons of X-ray astronomy". Russian Space Web. Retrieved 16 September 2016.
  2. ^ Gunter Dirk Krebs. "Spektr-RG (SXG)". Retrieved 4 February 2011.
  3. ^ ROSCOSMOS. "Spektr-RG (SXG)". Archived from the original on 20 June 2019. Retrieved 20 June 2019.
  4. ^ Howell, Elizabeth (13 July 2019). "Russia Launches Spektr-RG, a New X-Ray Observatory, into Space". Space.com. Retrieved 13 July 2019.
  5. ^ "Russia Successfully Launches Next-Generation Space Telescope". Radio Free Europe/Radio Liberty. 13 July 2019. Retrieved 16 July 2019.
  6. ^ Clery, Daniel (15 July 2019). "Update: Telescope designed to study mysterious dark energy keeps Russia's space science hopes alive". Science. American Association for the Advancement of Science. doi:10.1126/science.aay3154. Retrieved 16 July 2019.
  7. ^ a b "eROSITA Technical Performance". Max Planck Institute for Extraterrestrial Physics. Retrieved 14 June 2019.
  8. ^ a b Clery, Daniel (10 July 2019). "Telescope designed to study mysterious dark energy keeps Russia's space science hopes alive". Science. Retrieved 15 June 2019.
  9. ^ "Spectrum-RG/eRosita/Lobster mission definition document". Russian Space Research Institute. 30 October 2005. Retrieved 4 February 2011.
  10. ^ Zak, Anatoly (19 June 2019). "The Navigator satellite bus". Russian Space Web. Retrieved 13 July 2019.
  11. ^ Graham, William (13 July 2019). "Russian Proton-M launches Spektr-RG observatory". NASASpaceFlight.com. Retrieved 15 June 2019.
  12. ^ "SRG (Spectrum Roentgen Gamma) – Satellite Missions – eoPortal Directory". directory.eoportal.org. Retrieved 20 June 2019.
  13. ^ German X-ray telescope achieves ‘first light’. Spaceflight Now (23 October 2019). Retrieved on 2020-07-01.
  14. ^ "Новости. Первый свет обсерватории "Спектр-РГ"". www.roscosmos.ru. Retrieved 5 August 2019.
  15. ^ Statement on the status of the eROSITA instrument aboard Spektr-RG (SRG)
  16. ^ Russia stops deliveries of rocket engines to US, Roscosmos Head Says
  17. ^ "Russia plans to restart German telescope without permission | DW | 04.06.2022". Deutsche Welle. 4 June 2022. Retrieved 16 June 2022.
  18. ^ ART-XC / SRG overview. M. Pavlinsky; V. Levin; V. Akimov; A. Krivchenko; A. Rotin; M. Kuznetsova; I. Lapshov; A. Tkachenko; R. Krivonos; N. Semena; M. Buntov; A. Glushenko; V. Arefiev; A. Yaskovich; S. Grebenev; S. Sazonov; A. Lutovinov; S. Molkov; D. Serbinov; M. Kudelin; T. Drozdova; S. Voronkov; R. Sunyaev; E. Churazov; M. Gilfanov; B. Ramsey; S. L. O'Dell; J. Kolodziejczak; V. Zavlin; D. Swartz. Proceedings Volume 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray; 106991Y doi:10.1117/12.2312053 6 July 2018.