Soyuz-2 rocket launches the final GLONASS-M satellite
The Russian military personnel launched the 61st and the last satellite in the GLONASS-M series for the nation's orbital navigation network. The Soyuz-2-1b/Fregat rocket lifted off from Plesetsk Cosmodrome on Nov. 28, 2022. Slightly more than three and a half hours later, the GLONASS M-61 satellite should be released into its circular orbit about 19,000 kilometers above the Earth's surface.
GLONASS-M No. 61 mission at a glance:
Preparing the mission
The GLONASS M-61 satellite was one of three last satellites relying on a pressurized platform to house onboard avionics, before more advanced spacecraft fully equipped with systems capable of operating in the vacuum of space took over the composition of the GLONASS network.
In December 2021, the official Russian media reported that the last GLONASS-M was taken out of storage for preparation for launch then expected as early as March 2022. At the time, the particular spacecraft was on the ground for a number of years and its further storage would likely require a refurbishment or cutting its orbital life span. At the same time, the GLONASS-M provided a backup to the new-generation GLONASS-K series, in case there was a problem with their production, in particular due to ban on the supply of space-rated electronics to Russia.
Upon completion of the series production, one of two available processing facilities for GLONASS-M satellites at ISS Reshetnev in Zheleznogorsk had been dismantled, leaving the second to perform the final launch compaign in 2022, before the company would fully switch its development and testing infrastructure to GLONASS-K and K2 series.
On Nov. 15, 2022, Russian authorities issued a warning to air and sea traffic for the launch scheduled between November 27 and 30. Three areas in the Komi Republic, including "Vashka" in the Udorsky District and "Zheleznodorozhny" between Knyazhpogostky and Kortkerossky Districts, had been declared danger zones. Soon thereafter, another danger area was declared in the Uvatsk District of the Tyumen Republic, where Soyuz rockets lifting off from Plesetsk would typically drop their core stages. The unidentified was expected on November 27, from 17:00 to 19:30 Moscow Time with backup dates on November 28, 29, and 30.
The declared areas were typical for drop zones used by several military missions originating from Plesetsk, including GLONASS and Meridian.
GLONASS-M No. 61 launch profile
The mission likely followed the routine ascent profile of the GLONASS launches. After several seconds of vertical ascent, the launch vehicle headed southeast to reach an orbit with an inclination of 64.77 degrees toward the Equator. The four boosters of the first stage separated around two minutes into the flight and were expected to fall at drop zone S-19 in the eastern section of the Arkhangelsk Region. Around 45 seconds later, as the vehicle left the dense atmosphere, the payload fairing protecting the satellite was commanded to split into two halves and its fragments probably targeted the S-20 drop zone in the Komi Republic of Russia.
The second (core) stage of the rocket continued firing until around 4.7 minutes into the flight, separating moments after the ignition of the RD-0124 engine on the third stage. Seconds later, the cylindrical aft section of the third stage split into three segments and separated as well. The core stage and the fragments of the aft section likely fell at the S-21 drop zone in the Omsk Region.
The third stage of the rocket completed its powered ascent and separated from the payload section nine minutes and 22 seconds after liftoff. Just short of orbital velocity, the third stage was intended to naturally reenter the Earth's atmosphere near the opposite side of the Earth from the launch site, with its flaming remnants projected to fall into the southern section of the Pacific Ocean.
Shortly after planned liftoff time, the Russian media confirmed the fact of the launch. Quoting a Ministry of Defense announcement, the reports said that the Russian Air and Space Forces, VKS, performed the launch of the Soyuz-2-1b rocket with a military spacecraft at 18:17 Moscow Time (1o:17 a.m. EDT), however, there was no immediate confirmation that ground assets began tracking the vehicle. It did come with another communique several hours after the launch, confirming that the spacecraft had separated from the Fregat upper stage. (Roskosmos later announced that the liftoff had taken place at 18:13:50 Moscow Time).
Space tug maneuvers
During GLONASS missions, the Fregat-M upper stage conducts three orbital maneuvers to deliver the spacecraft to its operational circular orbit more than 19,000 kilometers above the Earth's surface.
The first firing of the Fregat's main engine, lasting around 20 seconds, is initiated around a minute after the separation from the third stage. The maneuver inserts the stack into an initial parking orbit and, after a less-than-half-an-hour passive flight, the Fregat fires its main engine again, this time for around 9.5 minutes. The second maneuver stretches the original near-circular orbit, boosting its apogee (highest point) to a target altitude of more than 19,000 kilometers. The Fregat/GLONASS stack then climbs that trajectory for more than 2.5 hours before firing again. The third Fregat maneuver at apogee, lasting just under four minutes, makes the orbit circular, and should be followed by the separation of the satellite around 30 seconds after the completion of the maneuver.
The official announcement from the Russian Ministry of Defense issued around 3.5 hours after liftoff on November 28 said that ground control had established and maintained reliable telemetry communications with the satellite and all its systems functioned nominally.
Upon the release of the satellite, Fregat is programmed to conduct two maneuvers with its attitude-control thrusters, SOZ, to enter a burial orbit above its former satellite passenger.
The US Space Forces cataloged two objects associated with the launch like representing GLONASS M-61 and the Fregat upper stage after their separation:
On November 29, the official GLONASS web site added the new spacecraft to the list satellites comprising the constellation. It was the first official confirmation that the Nov. 28, 2022, Soyuz mission indeed carried the GLONASS. According to the list, the fresh spacecraft was placed into Plane 2, Position 16 of the constellation. Accordint ot the same web site, the satellite was declared operational on Dec. 22, 2022.
An artist rendering of the Uragan-M (GLONASS-M) satellite in deployed configuration. Credit: ISS Reshetnev
Soyuz lifts off from Plesetsk on Nov. 28, 2022. Credit: Russian Ministry of Defense
Fregat upper stage boosts Uragan (GLONASS-M) satellite into an initial orbit. Click to enlarge. Copyright © 2017 Anatoly Zak
Fregat and GLONASS-M satellite approach the release orbit. Click to enlarge. Copyright © 2017 Anatoly Zak
GLONASS-M satellite separates from the Fregat upper stage. Click to enlarge. Copyright © 2017 Anatoly Zak