Spektr-RG

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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. It follows on from the Spektr-R satellite telescope launched in 2011.

Background

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.

Overview

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, the first in the medium X-ray band less than 10 keV energies, and the first to map an estimated 100,000 galaxy clusters. 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.

Spacecraft

The Spektr-RG mission concept was published in 2005. 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. The observatory was integrated into a Navigator satellite bus, produced by NPO Lavochkin.

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).

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. The first light image of ART-XC was taken on July 30, 2019.

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.

In March 2022, Russia said they turned off one of the two telescopes aboard Spektr-RG (presumably eROSITA) upon request from Germany. In June, Dmitry Rogozin, the head of Roscosmos, said he planned to unilaterally seize control of the German telescope, saying German officials' "don't have a moral right to halt this research for humankind" and that they had "pro-fascist views". However Russian astrophysicist Rashid Sunyaev said doing so could damage the instrument and would add to mistrust.

In 2023 it was published that Spektr-RG found 17 new AGNs. In 2025 it was published that Spektr-RG found additional 11 new AGNs.

Instruments

Earlier proposal

Development of an early version of Spektr-RG was started in mid-1990s and was cancelled in 2002. Initial launch date was set to 1995, but later postponed as far as 2008, until it was finally cancelled in 2002. However, some of the instruments have been completed, e.g., an X-ray telescope by Leicester University (JET-X) and an ultraviolet telescope by Tel-Aviv University (TAUVEX).

The satellite would have been launched into a 51.5 degree orbit with an apogee of 200000 km and a period of four days, by a Proton-K rocket with a Blok DM-2 upper stage.

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Optical mission support

Russian

• BTA-6
• Caucasus Mountain Observatory
• RTT-150
• Sayan Solar Observatory
• International Scientific Optical Network

German

• Las Campanas Observatory
• Cerro Tololo Inter-American Observatory
• Paranal Observatory
• La Silla Observatory

References

References

1. Gunter Dirk Krebs. "Spektr-RG (SXG)".
2. Zak, Anatoly. (16 April 2016). "Spektr-RG to expand horizons of X-ray astronomy". Russian Space Web.
3. ROSCOSMOS. "Spektr-RG (SXG)".
4. Howell, Elizabeth. (13 July 2019). "Russia Launches Spektr-RG, a New X-Ray Observatory, into Space". [[Space.com]].
5. (13 July 2019). "Russia Successfully Launches Next-Generation Space Telescope". Radio Free Europe/Radio Liberty.
6. Clery, Daniel. (15 July 2019). "Update: Telescope designed to study mysterious dark energy keeps Russia's space science hopes alive". American Association for the Advancement of Science.
7. "eROSITA Technical Performance". [[Max Planck Institute for Extraterrestrial Physics]].
8. Clery, Daniel. (10 July 2019). "Telescope designed to study mysterious dark energy keeps Russia's space science hopes alive". [[Science (journal).
9. (30 October 2005). "Spectrum-RG/eRosita/Lobster mission definition document". [[Russian Space Research Institute]].
10. Zak, Anatoly. (19 June 2019). "The Navigator satellite bus". Russian Space Web.
11. Graham, William. (13 July 2019). "Russian Proton-M launches Spektr-RG observatory". [[NASASpaceFlight.com]].
12. "SRG (Spectrum Roentgen Gamma) – Satellite Missions – eoPortal Directory".
13. [https://spaceflightnow.com/2019/10/23/german-x-ray-telescope-achieves-first-light/ German X-ray telescope achieves ‘first light’]. Spaceflight Now (23 October 2019). Retrieved on 2020-07-01.
14. "Новости. Первый свет обсерватории "Спектр-РГ"".
15. [https://www.mpe.mpg.de/7856215/news20220303 ''Statement on the status of the eROSITA instrument aboard Spektr-RG (SRG)'']
16. [https://www.spacedaily.com/reports/Russia_stops_deliveries_of_rocket_engines_to_US_Roscosmos_Head_Says_999.html ''Russia stops deliveries of rocket engines to US, Roscosmos Head Says'']
17. (2022-06-04). "Russia plans to restart German telescope unilaterally".
18. (2023-02-01). "New Active Galactic Nuclei Detected by the ART-XС and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys". Astronomy Letters.
19. (2024-05-01). "New Active Galactic Nuclei Detected by the ART-XC and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys. Part 2". Astronomy Letters.
20. !! [[Astronomical Roentgen Telescope -- X-ray Concentrator. 10.1117/12.2312053 6 July 2018.
21. (2007). "Space Exploration 2008". シュプリンガー・ジャパン株式会社.
22. (4 August 2000). "Spectrum-X-Gamma". [[DTU Space]].
23. (17 June 2009). "Leicester's role in Russian satellite programme revealed as UK's largest telescope goes to Science Museum". [[DTU Space]].
24. http://www.sstd.rl.ac.uk/project/jet-x/ {{Bare URL inline. (May 2022)
25. http://www.aip.de/groups/xray/sodart/ {{Dead link. (February 2022)