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Spektr-RG to fly on a refurbished rocket stage

Russia's flagship space observatory, Spektr-RG, will be launched with a space tug which had passed its original operational warranty and had to be refurbished for the task. The Block DM-03 upper stage required new certification for flight before it could be authorized to carry the irreplaceable X-ray telescope which took nearly a decade to build. Following its launch on a Proton rocket, Block DM-03 will have the critical task of boosting the observatory from its initial parking orbit into deep space, toward a Lagrange L2 point behind the Earth relative to the Sun.

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Block DM-03 architecture with a generic payload.

After the 2016 decision to switch the planned Spektr-RG launch from the Zenit-Fregat rocket to the Proton-Block DM vehicle, Roskosmos State Corporation made plans to use a Block DM-03 No. 4L upper stage, which had been manufactured in 2011 on an order from the Russian Ministry of Defense. The stage was likely intended for a trio of the Uragan-M satellites for the GLONASS navigation network, but it had remained unused because of a reduced demand for replacements.

At the time, the Block DM-03 No. 4L, along with a similar vehicle -- No. 3L -- was in storage at the Experimental Production Plant, ZEM, in Korolev near Moscow. (The ZEM plant mass produces the hardware developed at RKK Energia, including Block DM series.)

The guaranteed life span for the storage and use of Block DM-03 No. 4L was to officially expire on Nov. 23, 2018, which meant that if the launch of the Spektr-RG mission would not take place as then scheduled in September 2018, the upper stage would have to be re-certified for flight after that date. As of the end of 2017, it was increasingly clear that Spektr-RG would not be ready for launch before 2019, thus requiring to re-certify Block DM-03 No. 4L for flight.

However, by 2017, the Soviet-era diagnostics equipment for the Block DM series at the ZEM plant reached such an old age that it had to be upgraded first, before conducting any further testing of vehicles No. 3L and 4L.

To make matters worse, as of September 2017, RKK Energia did not even have the formal permission from the Ministry of Defense to modify the Block DM No. 4L for the Spektr-RG spacecraft. There was also no funding at the time for extending the guaranteed life span of the stage beyond November 2018.

In September 2017, RKK Energia requested 73,785 million rubles (approximately $1.3 million) from Roskosmos to refurbish checkout and power supply components in the diagnostics facility for the Block DM series. This money would also pay for upgrading the diagnostics system for the Block DM series with new computers to check the flight control system aboard Block DM-03.

RKK Energia also requested Roskosmos an additional 35.2 million rubles (approximately $0.6 million) to cover already incurred expenses for the maintenance of Blocks DM-03 No. 3L and No. 4L from 2013 to 2016.

Spektr-RG makes progress toward launch

On April 19, 2018, the press-service of the RKS Corporation said that it had delivered the Spektr-RG's radio system, BRK, and that the launch of the space observatory would occur in March 2019. By the end of May, both operational instruments of the observatory -- the Russian ART-XC and the German eRosita -- had been integrated with the flight version of the Navigator service module and tested. At the time, engineers were still working on a software update in the flight control system, BKU, of the spacecraft for handling the interface with the ART-XC instrument, industry sources said.

On May 29, NPO Lavochkin announced that from May 3 to May 21, a joint team of its engineers and specialists from the Space Research Institute, IKI, in Moscow and Max Planck Institute in Germany had conducted electric tests of the flight-worthy onboard radio complex, BRK, integrated with eRosita and ART-XC telescopes. According to NPO Lavochkin, the electric tests were necessary to check interaction between the service systems of the spacecraft and scientific instruments. The company also said that the spacecraft had been transferred to the assembly room and was a process of preparation for thermal and vacuum tests which had been scheduled to begin in July.

In the meantime, on May 22, Roskosmos abruptly cancelled a routine status meeting of participants in the Spektr-RG project scheduled in Moscow just two days later on May 24. According to the official explanation sent to the German side, a letter from the German space agency, DLR, requesting the review had come too late for the Russian side to process for the given date. However, the Russian leadership of the Spektr-RG project unofficially informed their German colleagues that the cancellation might be related to another management shakeup at the top of Roskosmos.

The sources familiar with the situation expressed optimism that the Spektr-RG had remained on track for its latest launch window at the end of March -- beginning of April 2019. At the time, the launch window for Spektr-RG was reported to be extending from February 27 to April 11, 2019.


A photo released on May 29, 2018, likely shows the flight version of the Spektr-RG's payloads and its Navigator service module during joint electric tests earlier that month.


(To be continued)


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Article and illustration by Anatoly Zak; Last update: July 1, 2018

Page editor: Alan Chabot; Edits: January 30, May 24, 2018

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General architecture of the Spektr-RG spacecraft as of 2017. Credit: NPO Lavochkin


Block DM-03 during processing in Baikonur. Credit: RKK Energia


Avionics of the BRK radio complex for the Spektr-RG spacecraft. Credit: NPO Lavochkin

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