Russia resumes GLONASS-K launch

Russia resumes the launch of GLONASS-K

The latest generation satellite for the Russian GLONASS navigation constellation reached orbit after a break of almost six years. The launch of the Soyuz-2-1b / Fregat rocket with the GLONASS-K No. 15L satellite took place on schedule on October 25, 2020, and the spacecraft is said to have been put into orbit around 3.5 hours later.

Previous GLONASS mission: GLONASS-K No. 12L

A full-scale model of the GLONASS-K satellite.

GLONASS-K No. 15L mission at a glance:

A long belated mission

GLONASS-K No. 15L is the third satellite in the K series, the latest version in the navigation constellation. Although two previous GLONASS-K-birds were launched in 2011 and 2015, a break of half a decade followed because components for the new generation spaceship were missing, e.g. B. specialized electronic units for aerospace or avionics. The shortage resulted from Western sanctions prohibiting the delivery of dual-use avionics to Russia after the Kremlin invaded Ukraine. In response, the Russian government launched an export replacement program aimed at providing indigenous electronics to the country’s industry. The effort was made difficult by the need, in some cases, to build entire factories from virtually scratch.

Around 2016, ISS Reshetnev, the main developer of GLONASS satellites, began redesigning the GLONASS-K variant for the components built in Russia. It is unclear to what extent the original GLONASS-K series relied on third-party components, but the new batch of spacecraft was not taken out of assembly until the late 2010s.

Before the end of 2019, GLONASS-K No. 15 was expected to start at the end of March 2020. Until February 2020 the mission was planned for May and at the beginning of April the launch was postponed to June 27th the planned delivery of the satellite to the launch site in mid-May 2020, RIA Novosti reported, citing unnamed sources. However, in the first half of May, the launch was postponed from June 27 to mid-July due to delays in the manufacture of the satellite. RIA Novosti said.

In early July it was reported that the launch date had been postponed to August 6 and the satellite was delivered to the launch site before the end of the month. Around July 10, ISS Reshetnev posted a video stating that the spacecraft would be shipped to the launch site within a few days. At the end of July, however, the start slipped from August 6 to the end of August 2020. RIA Novosti reported. The launch was postponed again in mid-August, this time until October 17, and thus pushed behind another Soyuz rocket mission with the Gonets-M satellites. At the beginning of October 2020, the start was planned for October 25, 2020.

On October 22, ISS Reshetnev announced that the GLONASS-K satellite was being integrated into its Soyuz-2 launcher, which was being prepared for rollout to the launch pad after approval by the state commission overseeing the flight.

Flight profile

The launch of the Soyuz 2-1b / Fregat rocket with the third GLONASS-K satellite took place according to plan on October 25, 2020 at 10:08:42 PM Moscow time from pad No. 3 at location 43 in Plesetsk. (If there is a 24-hour delay, the October 26 start time will be moved up to 10:04:38 PM Moscow time.)

A few minutes later, the Russian military confirmed through the official media that the pre-launch operations and the launch of GLONASS-K had proceeded as planned. The assets of the Titov Chief Test Center of the Russian Aerospace Forces (VKS) began tracking the vehicle at 10:11 p.m. Moscow time, the Defense Ministry said.

GLONASS-K’s recent launch likely emulated the flight profile of the previous missions. In this scenario, after a few seconds of vertical ascent, the launcher travels southeast to align its ground track with a 64.77 degree orbit to the equator. The four first stage boosters will separate approximately two minutes after the flight begins. Approximately 45 seconds later, the payload fairing protecting the satellite is instructed to split in half and fall off since the vehicle is above the detectable atmosphere at that point.

The second (core) stage of the rocket continues to fire until about 4.7 minutes after the start of flight and separates the moments after the RD-0124 engine has fired on the third stage. Seconds later, the cylindrical rear section of the third stage is divided into three segments and also separated.

The rocket’s third stage will complete its powered ascent and separate from the payload section nine minutes and 22 seconds after liftoff. The almost empty booster flies just before the orbital speed and penetrates naturally back into the earth’s atmosphere near the opposite side of the earth from the starting point. The burning remains are said to fall in the southern part of the Pacific Ocean.

Within an hour of launch, the Russian military’s official television station reported that the Fregat upper school had separated from the Soyuz-2-1b launcher as planned.

Space towing maneuvers

During a typical GLONASS mission, the Fregat-M upper stage performs three orbital maneuvers to bring the spaceship into its operational orbit more than 19,000 kilometers above the earth’s surface.

The first ignition of the Fregat main engine, which lasts about 20 seconds, is initiated about a minute after disconnection from the third stage. The maneuver inserts the stack into an initial parking lane and after less than half an hour of passive flight, the Fregat fires its main engine again, this time for about 9.5 minutes. The second maneuver extends over the original nearly circular orbit and increases its climax (highest point) to a target altitude of more than 19,000 kilometers. The Fregat / GLONASS stack will then climb onto this trajectory for more than 2.5 hours before firing again. The third Fregat maneuver at apogee, which lasts just under four minutes, makes the orbit at the newly reached altitude circular and should be followed by the separation of the satellite about 30 seconds after the maneuver is complete.

According to the flight program, the GLONASS-K No. 15 was scheduled to separate from Fregat on October 26, 2020 at 1:40:31:54 AM Moscow time (6:40 p.m. EDT on October 25). Within half an hour, the Russian military confirmed that the Fregat had successfully put the GLONASS-K satellite into a planned orbit.

When the satellite is released, Fregat is normally programmed to carry out two maneuvers with its SOZ attitude control thrusters in order to get into a grave orbit above its former satellite passenger.

(Sequel follows)