| Development of the Spektr-RG project
After the completion of all tests, the ART-XC telescope was finally delivered from RKTs Progress in Samara to NPO Lavochkin by December 27, 2016. In the meantime, Roskosmos hatched a very controversial plan to change the launch vehicle for the mission from Zenit to Proton. On December 2, Russian officials informed the project participants that the switch had been approved.
The ART-XC telescope shortly after arrival at NPO Lavochkin on Dec. 27, 2016.
In January 2016, NPO Lavochkin announced that the assembly of the Spektr-RG observatory would begin in the first quarter of the year. According to the company, the flight version of the spacecraft was undergoing electric and radio tests collectively known as ERTI. NPO Lavochkin also reported that the fueling and size prototype of the spacecraft had successfully completed tests in Baikonur, which revealed no need for design changes. The delivery of the two main instruments for the observatory was then expected in the second quarter of the year.
A prototype for the Russian-built ART-XC telescope was also undergoing a series of tests, while components of the flight version were in the final stages of production, NPO Lavochkin said. Due to presence of calibration sources aboard ART-XC, which use radioactive material to emit X-rays, the instrument had to be tested only at facilities certified to handle radioactive materials. However the traditional testing center of the Russian space industry -- NITs RKT in Peresvet near Moscow -- was not certified for such operations. As a result, the telescope had to be sent to RKTs Progress in the Southern Russian city of Samara, which further delayed the testing process. As of January, the delivery of the ART-XC after the tests was expected in May.
Soon thereafter, Roskosmos released footage showing the preparations of the the Spektr-RG spacecraft at NPO Lavochkin. The Chief Designer of the project Vladimir Babyshkin, was quoted as saying that the flight version of the observatory temporarily equipped with test versions of its instruments and radio system, was undergoing electrical tests.
In the meantime, engineers at the Max Planck Institute in Germany were completing the final calibration of the eROSITA instrument, before its delivery to Russia then expected sometimes after April 2016.
By the middle of October, the integrated tests of eROSITA were completed with flying colors and the team was waiting for a time slot to conduct the final electromagnetic compatibility tests on the instrument at a facility near Munich. It required postponing the air shipment of eROSITA to Moscow from November to around Christmas 2016.
In the meantime, the Russian-built ART-XC telescope and the Navigator platform (which would carry both instruments into space), were also reported to be in a high degree of readiness for flight. The instrument was finally delivered from RKTs Progress in Samara to NPO Lavochkin by Dec. 27, 2016.
The final assembly and the integrated testing of the Spektr-RG spacecraft was expected to take around nine months, making the spacecraft available for the delivery to Baikonur around October 2017.
As of fall of 2016, the official launch window was still extending from Dec. 18 to Dec. 24, 2017, however, the project team was favoring the launch window from March 1 to April 14, 2018. The latter opportunity provided the best visibility of the spacecraft by ground stations in Russia.
During 2016, Roskosmos hatched a very controversial plan to change the launch vehicle in the Spektr-RG mission. The Zenit rocket allocated for the flight was in storage at Site 42 in Baikonur, but its warranty had run out and it required refurbishment. By the fall of 2016, Russian officials entertained the possibility of using the remaining Zenit in Baikonur for the launch of the Angosat satellite as early as June 2017 to meet contractual obligations to the government of Angola. Under these circumstances, NPO Lavochkin began planning the switch of Spektr-RG from a Zenit/Fregat to a Proton-M/Block-DM rocket. During a review of the Spektr-RG status on October 12, NPO Lavochkin officials told the project participants that the move from Zenit to Proton would push back the launch date by nine months. Because NPO Lavochkin previously worked on switching the third Elektro-L satellite from Zenit to Proton, the company's engineers had already gained some experience in the necessary procedures. However some new tests and simulations could be necessary to validate the new flight scenario for Spektr-RG.
On December 2, during a technical meeting at NPO Lavochkin, Russian officials informed the Spektr-RG participants that Roskosmos had made the official decision to switch the launch to a Proton/Block-DM vehicle. According to the new launch scenario, the 11S861-03 (Block DM-03) version of the upper stage would be used in the mission. Both, the Russian and German scientific teams involved in the Spektr-RG project, expressed serious concerns about the move, but they had little leverage in the matter. According to the agreement between the German space agency, DLR, and Roskosmos, the two sides have to inform each other in advance on major changes in the project, but this clause gave DLR only slim chances to reverse the decision, industry sources said. Due to the almost inevitable delay of the launch beyond 2017, DLR would also have to decide whether to ship eROSITA telescope to Russia before the end of 2016.
Footage released at the beginning of 2016 shows what appears to be a test prototype of the Russian-built ART-XC telescope electrically connected to the Navigator service module (right). Click to enlarge. Credit: Roskosmos
Assembly of the Navigator service module for the Spektr-RG mission at NPO Lavochkin. Click to enlarge. Credit: Roskosmos