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|Proton delivers the second Blagovest satellite
The first mission of the Proton rocket in 2018 successfully delivered the Blagovest-12L spacecraft for the four-bird constellation of military communications satellites deployed in the geostationary orbit 36,000 kilometers above the Earth's surface. The liftoff took place as scheduled on April 19, 2018, at 01:12 Moscow Time (06:12 p.m. EDT). According to GKNPTs Khrunichev, it was the 417th launch of the Proton rocket.
Blagovest No. 12L mission at a glance:
Preparing the second Blagovest satellite
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 more satellites in the series in 2017 and by the fourth in the first quarter of 2018. At the beginning of August 2017, Testoedov told Russian media that the second satellite -- Vehicle No. 12L -- was scheduled for launch at the end of 2017. Another pair of Blagovest satellites was then shifted to 2018, Testoedov said at the time.
In the middle of 2017, ISS Reshetnev announced that the second Blagovest satellite had entered electric and thermal testing at the company's GVU-600 vacuum chamber. The tests were to last several weeks. The launch was then planned for Dec. 25, 2017, but by the beginning of November of that year, it had to be postponed until Feb. 2, 2018, at the earliest. The mission was then set for March 22.
By the end of January 2018, the launch was re-scheduled to April 4, but was expected to drift further. As of the first week of February, the shipment of the satellite to Baikonur was scheduled in the second half of that month, followed by a 45-day processing cycle at the launch site. During a mission management meeting on February 14, the launch was projected for not earlier than April 22, but by the beginning of March, the mission was set for April 19.
The spacecraft finally left the campus at ISS Reshetnev on March 1, 2018, and was flown to Baikonur to kick off the launch campaign.
On April 10, the payload section, including the Blagovest satellite and the Briz-M upper stage, was integrated with the three booster stages of the Proton-M launch vehicle and the integrated tests of the fully assembled rocket were conducted on April 11. The rocket was rolled out to Pad 24 at Site 81 in Baikonur on the morning of April 15, 2018.
Blagovest No. 12L lifts off
A Proton-M rocket with a Briz-M upper stage carrying Blagovest No. 12L lifted off as scheduled from Pad 24 at Site 81 in Baikonur Cosmodrome on April 19, 2018, at 01:11:59.971 Moscow Time (6:12 p.m. EDT on April 18). The first, second and third stage of the launch vehicle operated for less than 10 minutes, releasing the payload section, including the upper stage and the satellite, into a ballistic trajectory just short of orbital velocity.
Practically immediately after that milestone, the Russian Ministry of Defense confirmed that the liftoff had occurred at 01:12 Moscow Time and the upper stage with the spacecraft had separated from the third stage of the Proton-M rocket at 01:22 Moscow Time. Col. General Aleksandr Golovko, the Commander of the Russian Space Forces and the Deputy Commander of the Russian Aerospace Forces, VKS, supervised the launch from Baikonur, the Russian Ministry of Defense said.
In the meantime, around 1.5 minutes after the separation from the third stage, the Briz-M fired its own engine for less than four minutes to reach an initial parking orbit. It then made a swing around the Earth before firing again, this time for 17.5 minutes. The maneuver pushed the stack into a highly elliptical orbit, which the vehicle continued to climb for more than two hours. Between 02:43 and 02:51 Moscow Time, the Russian MMT-9 KFU telescope cluster in Nizhniy Arkhyz tracked the Briz-M/Blagovest stack along its expected trajectory.
The Briz-M's engine then fired again for nearly 18 minutes, this time, stretching the orbit so that its apogee (the highest point) ended up at an altitude of the geostationary orbit 36,000 kilometers above the Earth's surface. Shortly after the completion of its third maneuver, the space tug jettisoned its nearly empty external tank. (A fragment was later tracked by NORAD in an expected 387 by 35,686-kilometer orbit with an inclination 48.652 degrees toward the Equator.)
The remaining stack then climbed passively for five hours, before Briz-M initiated its fourth and final engine firing lasting nearly 14 minutes.
The maneuver circularized the orbit and tilted the inclination to match the plane of the Equator, getting the spacecraft ready for separation from Briz slightly more than a minute after the fourth Briz firing.
Shortly after the release of the spacecraft, the Ministry of Defense confirmed that ground control facilities of the Russian space forces had established reliable communications with the spacecraft and that all its systems were functioning well. Following the spacecraft acquisition, it received the official designation Kosmos-2526.
Around the same time, the satellite developer, ISS Reshetnev, identified the newly launched spacecraft as Blagovest No. 12 and confirmed that it communicates with ground control and all its mechanical devices had been deployed and it maintained a proper solar orientation.
The ascent to orbit for the Blagovest 12L mission was planned according to the following timeline:
The Blagovest-12L satellite was expected to be released from its Briz-M stage into a geostationary orbit over a point located between 53 and 54.3 degrees East longitude over the Equator. The spacecraft would then have to move to a point at 80 degrees East, where it would undergo testing, before proceeding to its operational position 128 degrees East longitude.
Post-launch trajectory measurements showed that Briz-M had delivered Blagovest-12L into an orbit within the required specifications, but the satellite had a minor easterly drift of around 2.3 degrees per day. That motion was expected to be adjusted in the near future to bring the satellite to its temporary testing position, which also happens to be to the east from its release point from the Briz-M upper stage.
After a five-day embargo on the firings of the satellite's electric engines, the maneuvers began as planned on April 25, 2018. At the time, the spacecraft was expected to arrive at its orbital testing location between May 7 and May 10, 2018. Up to 20 firings of three low-thrust ion engines were planned to bring the eccentricity and the inclination of satellite's orbit close to zero. During the same period, flight controllers would have three windows, on April 26, May 2 and May 6 to reassess the actual orbital parameters of the satellite and adjust orbital maneuvers based on the latest trajectory measurements.
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A Blagovest satellite under assembly and testing. Credit: ISS Reshetnev
Blagovest No. 12L leaves the assembly plant in Zheleznogorsk on March 1, 2018. Credit: ISS Reshetnev