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Russian space science gets reborn
Triumphing over three decades of historic cataclysms, economic problems and social cynicism, Russian astrophysicists re-invaded the outer space with their first 21st-century orbital observatory. The historic importance of the Spektr-R mission, which successfully reached orbit on July 18, 2011, was difficult to overestimate. It is enough to say that the last time Russian scientists had a dedicated spacecraft of comparable significance working in space, the USSR had still been in existence and today's young adults had not been born yet. Since then, the Russian space science was largely written off by a wider public, as the nation's scientific spacecraft inherited from USSR had remained grounded by economic foes, social neglect and mismanagement resulting in the virtual decimation of the country's scientific potential. Only with a gradual improvement in funding in mid-2000s, Moscow-based NPO Lavochkin and its partners managed to jump-start most crucial scientific projects, with the Spektr-R radio-telescope at the top of the priority list.
Spektr-R lifts off
Spektr-R lifts off on July 18, 2011.
A Zenit rocket carrying the Spektr-R satellite lifted off into cloudless sky as scheduled on July 18, 2011, at 06:31:17.91 Moscow Summer Time (10:31 p.m. EST on July 17) from Site 45 in Baikonur Cosmodrome, Kazakhstan. The first stage of the rocket separated around two minutes into the flight. The shutdown of Zenit's main engine on the second stage was confirmed 430 seconds after the liftoff, followed by the normal burn and a shutdown of the steering engines of the stage 520 seconds in flight. The Fregat upper stage and the Spektr-R stack then separated in its initial parking orbit. Following further maneuvers, Fregat released Spektr-R in a seemingly correct orbit at 09:06:58.6 Moscow Decree Time on July 18, 2011.
The planned launch sequence for the Spektr-R mission on July 18, 2011 (Moscow Summer Time):
According to NPO Lavochkin, a prime-developer of the Spektr-R observatory, the first communication session with the spacecraft was successful. In the meantime, Russia's official RIA Novosti news agency quoted the head of NPO Lavochkin, Viktor Khartov, as confirming the opening of the observatory's solar panels, the establishment of the correct attitude control relative to the Sun and reliable contacts with ground stations in Medvezhi Ozera and Ussuriisk. Khartov promised a switch to a three-axis attitude control three days in the mission and the opening of the main telescope antenna two days later.
Around noon Moscow Time, on July 22, 2011, a poster on the online forum of the Novosti Kosmonavtiki magazine reported that the crucial operation of the opening of the giant flower-like antenna onboard Spektr-R/Radioastron had began. The slow-motion process was expected to take hours, however around an hour and half later, the official Russian media hurried with reports that the opening had been completed. The official RIA Novosti news agency then quoted the chief designer of the Radioastron project, Vladimir Babyshkin, as saying that the ground control had received the first telemetry confirming that the opening of antenna petals had been underway. Unofficial reports said that the opening had been almost completed, however latches of petals, which would hold the dish in open position, had failed to close requiring to repeat the process. Several following attempts to lock the antenna apparently also failed, unofficial sources said. Flight controllers several times commanded the petals to move slightly toward folding position and then move back into the open position, however a required signal for closing of latches at the tips of petals still did not come. The antenna was finally left in an open but unlatched position.
A special meeting at NPO Lavochkin was scheduled for the next morning, around 09:00 Moscow Time, to evaluate the problem. According to sources at FIAN institute, which led the observatory's scientific program, the radio telescope would still be able to conduct its scientific studies despite an unlatched antenna, with some minor deterioration of data.
On the morning of July 23 (Moscow Time), a new attempt to deploy the antenna was made and, this time, it quickly resulted in a successful completion of the operation. According to postings on a web forum of the Russian astronomical community, all latches of the antenna had been fully engaged, triggering necessary confirmation signals from onboard sensors. Russia's first space observatory was open for business. According to sources involved in the project, during a break in the opening effort, the spacecraft was reoriented in space so that its main antenna was exposed to the Sun and the heating could alleviate some tension in the mechanism caused by extremely low temperatures. During the final operations, the opening mechanism was applying the maximum load of 1,200 kilograms onto the petals, instead of nominal 600 kilograms. However, in the previous attempt even that pressure reportedly failed to complete the opening.
Besides extremely low temperatures, the resistance of thermal protection layers, which might had not been adequately represented during ground tests, was considered as a potential culprit in the deployment problems. Finally, some slight errors in the mass-negating mechanism, which was designed to imitate the conditions of weightlessness on the ground, might had made it too easy for the antenna to open during pre-flight tests.
A successful opening of the main radio telescope antenna was followed by activation of other instruments onboard the spacecraft. The Space Research Institute, IKI, in Moscow reported that the activation of the Plasma-F package started on July 25, 2011, with the powering up of the SSNI-2 unit for gathering, storage and processing of scientific information. Other components of the complex were to be turned during the next week or two, IKI said. The magnitometer MMFF and the MEP particle detector were both said to be activated on July 30, 2011, however the MMFF detector returned no data, even though a special deployable boom holding the instrument had apparently released as planned.
On July 25, 2011, the guidance mechanism of the high-gain antenna onboard Spektr-R was disconnected from its launch stowage position and the device could now move freely to track ground stations. A day later, RIA Novosti news agency quoted the head of Radioastron project, Nikolai Kardashev, promising the opening of a specialized channel for the transmission of science data from Spektr-R spacecraft by August 4.
Following the calibration of the space-based radio telescope, the regular scientific data from the observatory could start coming at the end of September - beginning of October 2011, Kardashev said. (497)
The first attempt to establish a communication channel for downlinking scientific data from Spektr-R to the ground station in Pushino took place on Aug. 4, 2011. However even though the 22-meter radio telescope in Pushino was powered up, the attempt had to be postponed. Ground controllers found temperature onboard the telescope around -15 degrees C - considerably lower than nominal 0 - 20 degrees C required for normal operations.
The main radio-telescope antenna of the Spektr-R spacecraft had an electric heating system, consisting of 27 electric lines for all petals, however it failed to activate. As a result, the mirror could experience a change in temperatures reaching 100 degrees.
To partially compensate for the problem, mission control left the deployment ring, which pulls the petal under tension.
Mission controllers took actions to warm up the spacecraft, however the progress was too slow, requiring to postpone the delivery of science data until the next available window on August 13. Still, mission officials said that the spacecraft could operate within a range of temperatures from -25 to +70 degrees C.
According to unofficial reports, a critical hydrogen frequency standard onboard Spektr-R was also activated with a delay due to lower than expected temperatures.
Problems with secondary instruments
On Aug. 5, the Russian-Czech BMSW instrument was also successfully activated. Unfortunately, the MMFF magnitometer did not provide any data. At the same time, the MEP instrument was affected by the overall spacecraft thermal control problems, because the attitude control mode relative to the Sun, which was adopted during the mission often caused the instrument's saturation.
Initial communications tests between the spacecraft and ground control were limited to downlinks at 8.4 Gigahertz dedicated to the transmission of technical data only. The transmission of actual science data at a frequency of 15 Gigahertz was scheduled to take place for the first time on August 18. (504) On that day, NPO Lavochkin did announce that attitude control flywheels onboard Spektr-R had been tested and that ground controllers had been monitoring temperature onboard the spacecraft under conditions of constantly changing orientation relative to the Sun. There were also efforts to establish more precisely the satellite's orbital parameters on the basis of ground tracking information and checks of high-volume radio channel of the radio telescope. The company's press-release promised testing of science data transmission to begin in September. In the meantime, according to the project's sources, during the night from August 21 to August 22, 2011, a transmitter onboard Spektr-R was used successfully for the first time to downlink data to the receiving station in Pushino.
On Sept. 27, 2011, the Spektr-R telescope started scientific observations capturing its "first light" from the brightest natural radio source in the sky known as Cassiopeia A, an ancient exploded star. The telescope scanned across the supernova remnant in two perpendicular directions. Signal in two bands of 92 and 18 cm (two circular polarization per band) was successfully detected in the total power mode.
During November 2011, ground control conducted testing of scientific payloads, calibrated high-capacity data transmission channels between the spacecraft and the Pushino science ground station and measured parameters of the radio-telescope. In the same month, the spacecraft conducted its first interferometric observations.
During December, the Spektr-R underwent successful calibration in the interferometric mode with ground-based telescopes, which opened door to first scientific observations in January 2012.
Adjusting the mirror
Before the completion of the main scientific program, project officials considered an attempt to reduce the tension in the antenna's ring-shaped deployment mechanism in the hope of fixing some deformation of the mirror, even though it was more likely caused by the uneven exposure of the mirror to harsh temperatures changes in space without an operational heating system.
The problem was especially pronounced during the observations at the shortest range of radio waves - 1 centimeter, which led to a loss of effective gathering area of the mirror between three and four times. Fortunately, the interferometer's accuracy was reduced only by a factor of two. As a result, the main scientific tasks had been preserved. Scientists also learned to accumulate the signal much longer than originally planned, which allowed to compensate for the problem in big extent.
In theory, by adjusting the tension of individual petals via strings of the deployment mechanism, the surface of the mirror could be corrected. However, the risk of distorting the operational instrument, which could jeopardize the entire scientific program, was recognized to be too high for the experiment.
The external tank of the Fregat upper stage, that delivered the Spektr-R observatory into orbit almost nine years earlier, exploded on May 8, 2020, generating at least 65 trackable debris, according to the US Space Command. At the time of a breakup, the fragment with an international designation 2022-037B was orbiting the Earth in a 422 by 3,606-kilometer orbit with an inclination 51.45 degrees toward the Equator, the US orbital tracking showed. On May 10, Roskosmos posted an official press-release confirming the disintegration of the Separable Tank Block, SBB, which took place between 08:00 ad 09:00 Moscow Time over the Indian Ocean, according to the State Corporation. The announcement listed the same orbital parameters as those calculated by the US tracking assets.
Spektr-R mission chronology:
2011 July 18: Spektr-R reaches orbit.
2011 July 23: The Spektr-R deploys its main antenna.
2011 July 25: The guidance mechanism of the high-gain antenna onboard Spektr-R is unlocked.
2011 Aug. 5: The Russian-Czech BMSW instrument successfully activated.
2011 Aug. 21-22: A transmitter onboard Spektr-R is used for the first time to downlink data to the science receiving station in Pushino.
2011 September: Flight testing of the Navigator service module on the Spektr-R spacecraft.
2011 Sept. 27: The Spektr-R telescope starts scientific observations capturing its "first light."
2011 October: Ground control completes testing of the Navigator service module on the Spektr-R spacecraft.
2011 November: Ground control conducts testing of the scientific payloads, calibrates high-capacity data transmission channels between the spacecraft and the Pushino science ground station and measures parameters of the radio-telescope.
2011 December: Spektr-R undergoes calibration in the interferometric mode with ground-based telescopes.
2012 January: Spektr-R conducts its first scientific observation in the interferometric mode.
2012 February: Spektr-R begins its early scientific program.
2012 February-March: Spektr-R conducts orbit correction to prevent reentry at the end of 2013.
2013 June: Spektr-R completes its early scientific program.
2013 Aug. 1: The Green Bank telescope in the US successfully establishes its first contact with Spektr-R, becoming only the second location worldwide capable of "listening" to the Russian space observatory.
2013 July 1 - 2014: Spektr-R conducts its most crucial scientific observations.
2014: Spektr-R begins its general scientific observation program.
2014 October: A Japanese-built amplifier begins experiencing a technical problem.
A Zenit rocket with the Spektr-R spacecraft rolls out to the launch pad on July 16, 2011. Credit: Roskosmos
A Zenit rocket with the Spektr-R spacecraft blasts off on July 18, 2011. Credit: Vesti 24
Below: A sequence of renderings illustrating a ride to orbit and deployment of the Radioastron observatory. Credit: NPO Lavochkin
An external tank separates from the Fregat upper stage.
The Fregat upper stage separates from Spektr-R, after delivering the observatory into its operational orbit.
Spektr-R deploys its solar panels.
Spektr-R prior to the antenna deployment.
An initial stage of the antenna deployment.
Spektr-R in fully deployed position. Credit: NPO Lavochkin