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The original Spektr-RG satellite

Not to be confused with the ultimately launched Spektr-RG satellite, a much larger spacecraft with the same name and a very similar mission had come painfully close to reaching the pad two decades earlier, before severe financial problems of the post-Soviet Russia relegated it to a footnote in the history of space exploration and scattered museum exhibits.

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Spektr-RG as it was envisioned in the 1990s.



The original Spektr-RG project at a glance (circa 1998):

Spacecraft liftoff mass
5,900 kilograms
Scientific payload mass
2,750 kilograms
Expected life span
At least 3 years
Pointing accuracy
1.5 arcminutes
Pointing stability
2.5 arcminutes
Total onboard power supply
2.1 kilowatts
Launch vehicle
Proton-K/Block DM
Launch site
Baikonur Cosmodrome
Orbital altitude
500 x 200,000 kilometers
Orbital inclination
51.6 degrees
Orbital period
approximately 4 days

Origin of the Spektr-RG project

A brainchild of the astronomical section of the Soviet Academy of Sciences, Spektr-RG (where RG stands for Roentgen-Gamma) was designed for astrophysics research. The project was proposed by Academician Rashid Syunyaev, who previously led a team of scientists working with astronomical payload of the Kvant module aboard the Mir space station.

According to one of the project veterans, the concept of the Spektr-RG spacecraft was first formulated at a scientific symposium in 1987, which was dedicated to the 30th anniversary of the First Artificial Satellite. Along with Syunyaev, Soviet scientists Yakov Zeldovich and Roald Sagdeev stood at the roots of the project. Spektr-RG was expected to follow the Granat X-ray observatory, which was launched on Dec. 1, 1989. It carried two Soviet X-ray telescopes ART-P and ART-S, as well as the French Sigma telescope and several detectors.

Spektr-RG ended up to be the first of several proposed observatories intended to be based on the 72Kh6 military satellite, originally developed for tracking missile launches from a highly elliptical orbit around the Earth and, therefore, having great ability to precisely home in its sensors on potential targets. For the purposes of astrophysics, the base spacecraft with a mass of 2.8 tons was renamed "AM" a short for "astrophysics module." The 450-kilogram truss adapter would be used to connect the AM module with its payloads. (118)

The Spektr-RG project was assigned the AM3 module, because AM1 was given to Spektr-R and AM2 to Spektr-UF. (479)

Spektr-RG mission


The main payload of the Spektr-RG mission, -- the SODART telescope -- was built and tested at NPO Lavochkin.

Although, the initial proposals for Spektr-RG were formulated after similar effort on the Spektr-R telescope, the former project soon moved to the first position, probably because of its quickly growing international team of scientists, who wanted to contribute their instruments to the spacecraft.

Ultimately, 20 organizations, representing Denmark, UK, Germany, Italy, US, Finland, Switzerland, Israel, Hungary, Kyrgyzstan, Canada and Turkey, joined the Spektr-RG project.

Although, it was still the mission focused on the X-ray section of the electromagnetic spectrum, Spektr-RG evolved into a multi-wave observatory spanning from ultraviolet to hard X-rays, benefiting several sub-fields of high-energy astrophysics.

The 5.9-ton spacecraft was to carry 2,750 kilograms of scientific instruments, including five telescopes: SODART, JET-X, MART-LIME, FUVITA, TAUVEX, as well as all-sky monitors MOXE in SPIN sensitive to X-ray and gamma radiation. The Proton/Block DM rocket had to insert Spektr-RG into a highly elliptical orbit with an apogee of 200,000 kilometers above the Earth's surface, a perigee of 500 kilometers and an inclination 51.6 degrees toward the Equator. With an orbital period of around four days, the satellite could work up to 80 hours at a time, free of interference from the Earth's radiation belts. In the meantime, the spacecraft could be pointed at up to 10 different targets a day. (403)

Summary of instruments approved for instllation aboard the original Spektr-RG spacecraft:

Sensitivity range
Angular resolution
Energy resolution
Effective area
Filed of
0.2 - 20 keV
2 arcmin
2,000 sq.cm (2 keV)
1,000 sq.cm (10 keV)
100 sq.cm (20keV)
40x40 arcmin
SODART-OXC (Bragg spectrometer)
0.16 - 0.42 keV
0.5 - 1.3 keV
2.0 - 5.3 keV
5.3 -11.6 keV
E/?E=35 - 50
300 - 700
10 (0.25 keV)
7 (0.8 keV)
17 (2.5 keV)
41 (6.1 keV)
SODART focal plane detectors
0.2 - 3 keV
25% at 2 keV
2 - 17 keV
13% at 6 keV
2.0 - 25 keV
18% at 6 keV
Si (li) array SIXA
0.5 - 20 keV
190 at 6keV
X-ray polarimeter (SXRP)
2 - 15 keV
JET-X X-ray telescope
0.3 - 10 keV
20 arcsec
140 eV at 6 keV
360 (1.5 keV)
140 (v keV)
40x30 arcmin
MART X-ray telescope
10 - 150 keV
8 arcsec
5% at 60 keV
800 sq.cm
6 x 6 deg
FUVITA UV-telescope
0.01 - 0.014 keV
10 arcsec
10 sq.cm
diam. 1.2?
MOXE all-sky X-ray monitor
2 -12
2.4 arcsec
20% at 6 keV
6 x 3 sq.cm
4π ster
TAUVEX UV telescope
0.0091 - 0.0037
4 arcsec
Variable filters
3 telescopes with 20-cm mirrors
54 x 54 arcmin
Gamma-ray burst detectors
Gamma-ray burst detector
20 - 3,000 keV
9% at 662 keV
5 x 132
4π ster
X-ray wide-field cameras
2 - 30 keV
3 arcmin
18% at 6 keV
2 x 80
2 x 40? x 40?
Optical detector
Visible light
1 arcmin
Sensitive to m<10
4? x 4?


On Dec. 31, 1987, the Soviet Academy of Science and Glavkosmos USSR (which was responsible for international alliances of the Soviet rocket industry) issued an official "Decision on the order of design and development of the Spektr series." It called for the launch of the Spektr-RG satellite in 1993, ahead of all other members of the Spektr family. (479)

At the time, the project was expected to have the following development milestones:

  • 1988: Completion of preliminary design;
  • 1989: Completion of the production documentation;
  • 1990: Completion of working prototypes for scientific instruments;
  • 1991: Ground testing of hardware.

However dwindling space science budget of the early 1990s, forced the Russian government to focus resources on the Mars-96 mission, which had an even higher international profile, at the expense of Spektr-RG, since it was not possible to fund both projects in parallel.

Death of the project


A payload section for the Spektr-RG spacecraft with the SODART telescope under assembly circa March 1998. The satellite's service module can be seen on the background in the center.

After the launch and the immediate loss of the Mars-96 spacecraft in November 1996, the Russian government attempted to boost its funding for the Spektr-RG project, but the real money continued coming irregularly and below the required budget even after giving Spektr-RG the highest priority among science projects in 1997. While international partners dutifully delivered their development prototype and, in many cases flight versions of science instruments, the service module of the spacecraft stayed unfinished at NPO Lavochkin.

Moscow struggled to fund the project despite considerable political pressure from international partners, including the weight of the Gore-Chernomyrdin commission on space cooperation between Russia and the United States, which reconfirmed its support for the Spektr-RG project in January and July 1996.

At that time, the payload of the mission were undergoing the second phase of integrated testing using engineering prototypes of the instruments delivered back in 1993. The US partners planned to deliver flight versions of the instruments in the Summer of 1996. In the summer of 1995, the US also provided IKI with the first part of the arhiving system and planned to deliver the second part in 1996. At the time, the launch of the observatory was promised in 1997, but by December of 1996, joint US-American documents were already citing the end of 1998 launch date. By that time, NASA was already loosing patience, stating that it would boost its funding for the project only when it sees the 12-month readiness of the spacecraft for flight. NASA promised to purchase near-real-time recording system for the project as soon as the flight version of the Spektr-RG was ready.

By that time, integrated tests of the scientific payload based on engineering model were still incompleted, but the assembly of the proto-flight model of the SODART telescope was declared finished.

In 1998, the financial default in Moscow delivered a mortal blow to the program. By that time, Western partners spent $300 million on their participation in three Spektr observatories, with most of these funds going to Spektr-RG.

In the wake of the financial crisis, Roskosmos still kept Spektr-RG at the top of the list of science projects, promising 95,000,000 rubles in 2000, according to a protocol of a meeting on the subject issued on April 13 of that year. However, the document now put off the launch date to 2002 with a footnote that it would depend on the actual funding. But, the money were not forthcoming.

As a "compensation" for the losses by foreign partners, Russia offered a Proton rocket to launch a similar European space telescope, known as Integral. Ironically, the high cost of the Proton was previously cited as one of the reasons for delays in the Spektr-RG project. (402)

Even some of the Russian scientists, who participated in the Spektr-RG project, decided to "jump the ship" and banked on the European observatory instead. In 1999, Roskosmos added 30 million rubles for the support of the project, essentially chanelling these funds for the procurement of a Proton rocket. Another 80 million rubles were promised in 2000 and 140 million in 2001. It is unclear how much of this money had actually been paid.

ESA provided Russian partners 25 percent of available observation time onboard Integral. The European spacecraft was launched without problems or considerable delays in 2002.

Strangely, the stalled Spektr-RG project was still promised 77.7 million rubles in 2001, along with 47.15 million rubles in "compensation" funds (apparently for previous years). Only on Feb. 13, 2002, the Space Council of the Russian Academy of Sciences, which oversaw all space sciene projects, essentially declared Spektr-RG dead, by stripping its priority status, though without a concensus among the council members.

By that time, another 165 million rubles were already allocated for the defunct project during its final year. Still, the majority of the Space Council argued that by 2006, the earliest date when Spektr-RG had a chance to fly, the new-generation AXAF Chandra observatory from NASA and the European XMM Newton would already deliver the kind of scientific data that would make Spektr-RG irrelevant.

Instead, the Academy of Sciences switched its priority to the Spektr-R project, hoping to launch it no later than 2007. In reality, it would not fly until the middle of 2011. (402)


Next chapter: Revival of the Spektr-RG project in the 2000s


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Article by Anatoly Zak; Last update: June 14, 2019

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Service module of the Spektr-RG satellite based on the 72Kh6 US-K/Oko spacecraft bus on March 3, 1998. Credit: IKI


Radiator system of the AM service module. Credit: IKI/NPO Lavochkin



The 450-kilogram truss system was designed to integrate the service module and scientific instruments of the Spektr-RG mission. Credit: IKI/NPO Lavochkin


A SODART telescope payload. Credit: IKI/NPO Lavochkin




A payload section integrated with the AO service module. Credit: IKI/NPO Lavochkin




The original Spektr-RG spacecraft is being prepared for vibration tests circa March 1998. Credit: IKI


Spektr-RG's sophisticated JET-X telescope became a museum exhibit. Click to enlarge. Copyright © 2010 Anatoly Zak




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