|Proton delivers first Blagovest military comsat
The second Proton mission of 2017 successfully delivered the first Blagovest communications satellite, according to the Russian Ministry of Defense. Blagovest is a Russian religious term meaning "good news." Due to the military nature of the payload, only limited information was released on the mission and no live coverage of the liftoff on August 17 was provided. According to the rocket manufacturer, it was the 100th launch of the Proton-M variant and the 414th mission since the introduction of the Proton family in 1965.
Blagovest No. 11L mission at a glance:
Preparing the first Blagovest for flight
A Blagovest satellite during testing of its antenna deployment.
As of May 2016, the head of ISS Reshetnev Nikolai Testoedov said that the first Blagovest satellite would be ready to fly before the end of that year, followed by two other satellites in 2017 and by the fourth in the first quarter of 2018.
The launch of the first Blagovest was planned for September and October 2016 and then the end of June 2017, however, it had to be delayed well into 2017, primarily due to problems with the engines of the Proton rocket. On July 3, 2017, ISS Reshetnev announced that the satellite had been delivered to the launch site. At the beginning of June, the launch was officially scheduled between July 24 and 31, but by the end of June, accumulating delays had already required a delay until at least August 10 and that date was then quickly switched to August 17.
According to sources familiar with the matter, the Blagovest launch campaign had to overcome a number of technical problems under a very tight deadline. During the assembly of the Proton's first stage, a wrong cable connection in the strap-on tanks pushed the preparations at least one day behind schedule. Next, engineers discovered problems with several avionics units requiring urgent air deliveries of replacements from Moscow. Even a dynamometric key used in processing turned out to be defective, while its hastily delivered replacement turned out to be foreign-made, which military controllers banned from operations.
Facing multiple problems, the team had to work overnights and over a weekend, but managed to complete the assembly at the Proton's processing complex on time for the rollout of the launch vehicle to Pad 24 at Site 81 on August 13. However the State Commission overseeing the launch and scheduled to convene on August 12, was yet to authorize the rollout to the pad and liftoff on August 17. Although there were no technical hurdles before the mission at that point, Pad 24 had been formally certified for operations only until July 31, 2017, industry sources said. Fortunately, a formal waiver extending the pad operations until July 31, 2019, was signed on August 10, clearing the way for the rollout of the rocket as originally scheduled. The vehicle was installed on the launch pad in preparation for liftoff at 01:07 Moscow Time on August 17, during a three-minute window. Another launch attempt could be made on August 18, if necessary.
The ascent to orbit for the first Blagovest mission was planned according to the following timeline:
Proton launches the first Blagovest satellite
A Proton rocket lifted off as scheduled from Pad 24 at Site 81 in Baikonur Cosmodrome on August 17, 2017, at 01:06:59.975 Moscow Time (6:07 p.m. EDT on August 16). The rocket carried the Blagovest No. 11L military communications satellite. The details of the ascent profile were not officially released, but on August 9, Russian authorities issued an advisory for air traffic to avoid a region in the Pacific Ocean, southeast of Japan. The closed area roughly matched the location for the expected splashdown of the rocket's third stage.
Around 10 minutes after the scheduled launch, the official RIA Novosti new agency reported that the rocket had lifted off with a military spacecraft. Col. General Aleksandr Golovko, the Deputy Commander of the Russian Air and Space Forces, VKS, oversaw the launch operations in Baikonur, RIA Novosti said. The agency quoted military officials as saying that all pre-launch operations and the liftoff of the launch vehicle had gone as scheduled.
According to the Ministry of Defense, the overall control of the mission was conducted by ground assets of the Titov Chief Test Space Center of the VKS. The Briz-M upper stage with the satellite separated from the third stage of the launch vehicle at 01:17 Moscow Time on August 17 (6:17 p.m. EDT on August 16).
Around the same time, ISS Reshetnev issued a press-release confirming that the launch of the Blagovest No. 11 satellite had taken place on time and the orbital insertion had been ongoing.
Several hours later, the Ministry of Defense declared the mission a success and released photos and video footage of the liftoff:
"The satellite launched for the purposes of the Russian Ministry of Defense from Baikonur Cosmodrome reached its planned orbit as scheduled and was taken under control of the ground assets of the space units of the Air and Space Forces," the Ministry of Defense said... "(Ground control) maintains reliable telemetry communications with the spacecraft. After establishing control (over the satellite), it was designated Kosmos-2520."
A few hours after the launch of the Blagovest satellite, NORAD released data indicating that the external tank from the Briz-M upper stage used in the mission was orbiting the Earth in a 399 by 35,698-kilometer orbit with an inclination of 48.6 degrees toward the Equator. Another maneuver later raised the perigee (the lowest point) of the satellite's orbit and further reduced the inclination, completing the four-burn ascent profile for the Briz-M stage.
On August 18, ISS Reshetnev published a press-release claiming that the Blagovest had reached its position in the geostationary orbit. "Upon reaching its operational orbit, the mechanical systems -- solar panels and antennas -- had been deployed," ISS Reshetnev said, "The spacecraft has oriented itself at the Sun and maintains stable telemetry communications (with ground control). Following the orientation of the satellite toward Earth, specialists will begin testing the operation of all its systems."
The NORAD radar confirmed that Kosmos-2520 (Blagovest) was in a 35,508 by 35,768-kilometer orbit with an inclination 0.1 degrees, which was close to a geostationary orbit, but still allowing the satellite to drift around two degrees per day in the easterly direction rather than synchronizing its movement with a single point on the Earth's surface, according to Jonathan McDowell, a space historian and satellite tracking expert.
According to Russian sources, that drift was a result of a routine inaccuracy in the orbital period resulting from the operation of the Briz-M upper stage. The post-launch orbital tracking by Russian specialists showed that the Briz-M had released its cargo into a slightly less than perfect orbit, but within required specifications for a fully nominal deployment of the satellite:
Behind the scene, Russian experts said that Blagovest would likely need between 25 and 30 days to reach its final destination. To do that the satellite would have to reverse its drift and begin moving westward. A 180-hour maneuver was required to give the satellite a drift rate of around 2.5 degrees per day, Russian engineers initially estimated. Each hour of the burn was to change the orbital period of the satellite by around five seconds. Simultaneously, the Blagovest was to correct some eccentricity (or deviation of its orbit from a perfect circle). That effort would require around seven maneuvers, but all of the orbit correcting could only begin on a sixth day of the mission, sources said.
As of August 22, the first orbital correction of the Blagovest satellite, lasting 150 hours (six days and six hours) using its xenon-burning electric engines was scheduled to begin on August 23, 2017. It was designed to reverse the satellite's drift with a speed of 1.5 degrees per day. During its westward movement, the spacecraft was also scheduled to perform 14 maneuvers to adjust its orbital inclination. Finally, nine firings of its electric engines were to be used to adjust the eccentricity of the orbit. The total number of maneuvers was to reach 24, but mission control could modify the plan based on the satellite's actual orbit. According to this scenario, Blagovest No. 11L was expected to reach its planned orbital position at 45 East on Sept. 17, 2017.
According to a poster on the Novosti Kosmonavtiki forum, Blagovest No. 11L began its maneuvers as planned. By the start of the day on Aug. 28, 2017, the satellite reversed its movement relative to the Earth's surface, reaching 69.8 degrees East longitude and continuing its drift westward with a speed of 0.5 degrees per day. At the end of the maneuver, it was expected to accelerate its movement to the West to a rate of 1.6 degrees per day.
The Blagovest No. 11L successfully reached its operational position at 45 degrees East longitude as planned on Sept. 16, 2017, industry sources told RussianSpaceWeb.com.
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The first Blagovest satellite during vacuum testing. Credit: ISS Reshetnev
Proton with Blagovest No. 11L is installed on the launch pad on Aug. 13, 2017. Click to enlarge. Credit: Roskosmos
Click to enlarge. Credit: Roskosmos
Service gantry is retracted from Proton shortly before liftoff on August 17, 2017. Click to enlarge. Credit: Roskosmos
Proton lifts off with Blagovest No. 11L. Click to enlarge. Credit: Roskosmos