Fifth GLONASS-K satellite lifts off
Russia launched a second satellite in 2022 to replenish its GLONASS navigation network. The GLONASS-K No. 17 satellite, which the fifth in the K seriers, lifted off on a Soyuz rocket from Plesetsk launch site in the early hours of October 10.
GLONASS-K No. 17L mission at a glance:
Fourth GLONASS-K mission
It reached the launch pad just two months after its predecessor, which likely indicates the that the GLONASS-K series reached serial production.
According to ISS Reshetnev in Zheleznogorsk, which builds GLONASS series, the integrated tests of the newly assembled Vehicle No. 17 started in June 2021. At the time, the launch of that particular satellite was expected before the end of 2021, however it depended on the status of other vehicles in the systems in orbit, the company said. The delivery of Vehicle No. 17 to the Plesetsk launch site eventually slipped to August and then September 2022 and its launch to October of that year. At the end of September, ISS Reshetnev confirmed that the spacecraft had indeed been delivered to the launch site.
In early October, local authorities in the Komi Republic posted a public warning about planned use of the Vashka drop zone in the Udorsky Region and the Zheleznodorozhny drop zone on the border between Knayzpogostky and Kortkerossky regions during the launch of a Soyuz-2 rocket on October 10. The safety survey of the area was scheduled for October 6 and 7, the press service of the environmental authority in the republic said.
The liftoff of the Soyuz 2-1b/Fregat rocket with the fourth GLONASS-K satellite took place as scheduled on Oct. 10, 2022, 05:52:32.531 Moscow Time (10:52 p.m. EDT on October 9) from Site 43 in Plesetsk. (In case of a 24-hour delay, there was a backup launch window on Oct. 11, 2022.)
The latest launch of GLONASS-K likely emulated the flight profile of the previous missions. Under that scenario, after several seconds of vertical ascent, the launch vehicle heads southeast to align its ground track with an orbit inclined 64.77 degrees toward the Equator. The four boosters of the first stage separate around two minutes into the flight and then fall in the Komi Republic.
Around 45 seconds later, the payload fairing protecting the satellite is commanded to split into two halves and drops off right after the vehicle exits the discernible atmosphere.
The second (core) stage of the rocket continues 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 splits into three segments and separates as well. All the fragments resulting from the separation of the second and third stage then fall in the Tobolsk and Uvatsk districts of the Tyumen Oblast (region).
The third stage of the rocket completes its powered ascent and separates from the payload section nine minutes and 22 seconds after liftoff. Flying just short of orbital velocity, the nearly empty booster naturally reenters 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.
According to the Russian military, the separation between the third stage and the Fregat took place at 06:01 Moscow Time on October 10 (11:01 p.m. EDT on Oct. 9, 2022).
Space tug maneuvers
During a typical GLONASS mission, 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 at the newly reached altitude and it 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 usually programmed to conduct two maneuvers with its attitude-control thrusters, SOZ, to enter a burial orbit above its former satellite passenger. Several hours after the launch, the Russian military confirmed that the maneuver had indeeed been performed.
After reaching its planned orbit, GLONASS-K No. 17L received a public designation Kosmos-2559.
A fully assembled GLONASS-K satellite circa 2020. Credit: ISS Reshetnev
Payload fairing of the Soyuz rocket with GLONASS-K No. 17 satellite shortly before the rollout of the vehicle from the assembly building.
Soyuz rocket lifts off with GLONASS-K No. 17 satellite on Oct. 11, 2022.
Ascent of a Soyuz rocket on Oct. 10, 2022, as seen from Finland. Click to enlarge. Credit: twitter.com/bloodmoose1 (used here with permission)