Soyuz-2 rocket launches the 59th GLONASS mission
After a 24-hour delay, the Russian military launched a fresh satellite to replenish the nation's orbital navigation network. The 59th mission to deploy the GLONASS constellation lifted off from Plesetsk Cosmodrome on a Soyuz-2-1b/Fregat rocket on December 11, 2019. Slightly more than three and a half hours later, the GLONASS M-59 satellite was released into its circular orbit about 19,000 kilometers above the Earth's surface.
GLONASS-M No. 59 mission at a glance:
Preparing the mission
The GLONASS-M No. 59 satellite was expected to be launched into the first out of three orbital planes occupied by the GLONASS constellation. The operational network normally contains eight spacecraft evenly distributed throughout each plane and the GLONASS M59 mission was reported to be targeting the fourth position in the first orbital plane, where it would replace Satellite No. 742 (Kosmos-2474), which was launched on October 2, 2011, but stopped functioning in August 2019.
The launch of GLONASS No. 59 was previously expected on December 2, 2019, but by the beginning of November 2019, the mission was postponed to December 10 of that year.
Between December 2 and December 6, Russian authorities issued several notifications to air traffic to avoid several areas that had also been closed for previous GLONASS launches.
The first attempt to launch the GLONASS M-59 mission was made on December 10, 2019. Based on postings on the online forum of the Novosti Kosmonavtiki magazine, it appeared that the liftoff was set for around 11:55 Moscow Time. However a problem with the third stage of the launch vehicle triggered an abort in the automated sequence around a minute before the planned liftoff. As a result, the launch was postponed to a backup window 24 hours later on December 11, 2019.
GLONASS-M No. 59 launch profile
The liftoff of the Soyuz-2-1b/Fregat-M vehicle with the GLONASS-M No. 59 satellite took place as scheduled on December 11, 2019, at 11:54:48.591 Moscow Time (3:54 a.m. EST) from Pad 3 at Site 43 in Plesetsk. It was the first mission originating from Pad 3 after years of renovations, following a launch accident in 2002.
The mission 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 were probably targeting to impact the ground at 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 separate 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 naturally reentered 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.
Several minutes after the planned liftoff time, the Russian media confirmed the fact of the launch. Quoting a Ministry of Defense announcement, the reports said that all pre-launch operations and the liftoff of the Soyuz-2-1b rocket had gone as planned and the assets of the ground control complex had been monitoring the liftoff and the flight of the rocket.
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.
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.
An artist rendering of the Uragan-M (GLONASS-M) satellite in deployed configuration. Credit: ISS Reshetnev
GLONASS-M satellite. Credit: ISS Reshetnev
A Soyuz-2-1b rocket is being prepared for the GLONASS M-59 mission in December 2019. Click to enlarge. Credit: Russian Ministry of Defense
A Soyuz-2-1b rocket with GLONASS M-59 satellite shortly before liftoff on December 11, 2019. Click to enlarge. Credit: Russian Ministry of Defense
GLONASS M-59 lifts off on December 11, 2019. Click to enlarge. 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