Soyuz delivers a pair of Galileo satellitesAfter a five-year break, the Soyuz rocket picked up the task of deploying the European satellite navigation system. The long-delayed 13th launch in the Galileo program lifted off from a tropical launch site in French Guiana on a Soyuz-ST-B rocket on December 4, 2021, carrying the 27th and 28th operational satellites for the constellation. It was the 26th launch of a Soyuz rocket from the coast of South America.
The 13th Galileo launch at a glance:
Galileo's 13th mission to complete the constellation
The satellites scheduled to be delivered during Galileo's 13th mission represented the first pair in the third and final batch of the first-generation spacecraft built for the constellation by the OHB SE company in Bremen, Germany. In total, Batch 3, whose production was approved in 2017, was expected to include 12 spacecraft. At the time of shipment to the launch site of the 27th and 28th satellites, all other satellites from the third batch were undergoing pre-flight testing, according to ESA. The 13th launch was to mark the transition of the Galileo constellation from what was characterized as "initial services" inaugurated in 2016 to "Full Operational Capability, FOC," ESA said. Within the FOC framework, the 27th and 28th spacecraft had the designations FOC Mission 9 No. 23 and 24, because the satellites launched in four earliest missions of the Galileo project were qualified as test spacecraft.
The FOC status in the Galileo system requires eight operational satellites and two spares in each of the three orbital planes of the system, which had not been achieved prior to the 13th launch.
In parallel with deploying FOC operations, the European Commission, which funded the original system, was also preparing for the introduction of the second-generation Galileo satellites, promising enhanced capabilities starting in 2024. In May 2021, the European Space Agency, ESA, managing the Galileo system on behalf of the European Commission, awarded two contracts worth total 1.47 billion Euro to Thales Alenia Space and Airbus to develop two dissimilar navigation satellites, forming a 12-spacecraft addition to the Galileo. The larger second-generation spacecraft were expected to feature electric engines and sport new digital systems, allowing their re-configuration in flight and providing better protection against jamming and other electronic warfare measures, ESA said. Generation 2 satellites were also designed to provide some emergency communications capabilities, according to ESA. Starting with Launch 14, Europe's yet-to-be-introduced Ariane-62 booster was scheduled to join the task of deploying the Galileo satellites.
Preparations for the 13th launch
A Soyuz-ST-B rocket is installed on the launch pad on Nov. 27, 2021.
As of April 2020, the 13th Galileo mission (and the 9th FOC mission) was planned to launch on Dec. 15, 2020, but it had to be delayed until early 2021 and by the beginning of 2021, the flight slipped to the middle of 2021 and then to October 2021. By March 2021, the launch was planned for the end of November of that year.
On Sept. 23, 2021, Roskosmos said that two Soyuz-ST rockets had been shipped to French Guiana and confirmed that the launch of Galileo satellites had been planned for November.
The two FOC-M9 Galileo satellites departed the ESTEC center in Noordwick, the Netherlands, where they were undergoing a three-month campaign of acceptance tests, for French Guiana aboard an Ilyushin-76 cargo plane on October 5. Upon delivery to the processing facility in Kourou, their fueling started on October 11.
On October 15, Roskosmos confirmed that the ship Tucan, with a pair of Soyuz rockets, had reached French Guiana and the launch of a Soyuz-ST-B rocket with two Galileo satellites was planned for December 1.
On October 27, specialists from RKTs Progress and the TsENKI ground infrastructure division of Roskosmos unloaded the boosters and started assembly of the first and second stages of the rocket. In the meantime, the Fregat upper stage for the mission was delivered to the FCube facility for fueling. The propellant loading operations were completed by November 22, when Fregat was scheduled for transfer to the S3B facility for integration with the satellites. Next, a pair of satellites was attached to their payload dispenser between November 16 and 17 and then mounted on Fregat between November 23 and 25.
A Soyuz rocket shortly before an aborted launch attempt on Dec. 3, 2021.
The rollout of the three-stage booster stack of the Soyuz-ST-B rocket to the launch pad started at 12:55 Moscow Time (6:55 a.m. local time in French Guiana.) on Nov. 27, 2021. The upper composite, including the Fregat upper stage, the satellites and the payload fairing, was delivered to the launch pad on the same day and integrated with the booster stages on November 29. On the same day, the Launch Readiness Review cleared the mission for launch.
However, due to prohibitive winds at high altitude, on November 30, the launch was delayed from December 1, at 21:37:27 French Guiana time until at least December 2, at 21:27 French Guiana time.
By the end of the day on December 1, Arianespace announced that weather conditions in Kourou had been acceptable for re-starting the preparations for launch. However, the decision for fueling the launcher, scheduled five hours ahead of liftoff, would be dependent on another review of weather conditions, according to the company. The doubts around the weather conditions appeared to be persisting during much of the day on December 2, however soon after the fueling of the rocket was supposed to begin at L-5 hours, Roskosmos announced that the launch attempt had been postponed until December 4 at 03:23 Moscow Time (21:23:22 French Guiana time on December 3) due to not readiness of a French ship-based telemetry receiving station. Arianespace did confirm that unavailability of a tracking station downrange from Kourou had required to postpone the launch. On the morning of December 3, the company announced that the anomaly at the ground station had been resolved, but the final decision about the fueling and launch of the rocket would be taken at L-5 hours before the scheduled liftoff.
On December 3, the countdown came within 10 minutes from liftoff, but weather conditions, in particular high winds and lightning, forced to postpone the mission until December 4, at 21:19:20 French Guiana time.
Flight profile of the 13th Galileo mission
Following vertical liftoff under the combined thrust of the four RD-107 engines on the first stage and the single RD-108 of the second (core) stage, the launch vehicle headed northeast over the Atlantic Ocean, matching its ground track to an orbit inclined 57.09 degrees to the plane of the Equator.
The four boosters of the first stage separated 1 minute and 57 seconds after liftoff, while the core booster of the second stage continued firing. The payload fairing protecting the payload split into two sections and separate 3 minutes and 55 seconds after liftoff during the operation of the second stage.
The third stage will ignite moments before the separation of the second stage, firing its four-chamber RD-0124 engine through a lattice structure connecting the two boosters and ensuring a continuous thrust during the separation process.
Nearly 10 seconds after the second and the third stages parted ways at an altitude of around 150 kilometers, the aft section of the third stage split into three segments and fell off 4 minutes and 54 seconds after liftoff.
The third stage of the launcher separated from the upper composite 9 minutes and 23 seconds after launch on a ballistic trajectory just short of orbital velocity. A minute later, the Fregat fired its main engine for the first time to reach an initial orbit.
After its first burn which was completed 23 minutes 42 seconds after liftoff, the upper composite entered a slow spin during a passive phase of the flight lasting around three hours 19 minutes as the stack was climbing along its trajectory.
Then, 3 hours 42 minutes and 25 seconds after launch, Fregat ignited its engine once again to circularize the orbit at an altitude just shy of 30,000 kilometers. Around 4.5minutes later (at 3 hours 46 minutes 50 seconds after launch), the Fregat complete the burn followed by the separation of the two satellites in opposite directions from the Fregat's payload dispenser 3 hours 51 minute 50 seconds after liftoff.
At the end of the mission, the Fregat will be automatically emptied of any remnants of its pressurized contents and deactivated.
The Galileo satellites normally use their own propulsion system to enter their operational orbit and are brought into service in around three months after launch.
Basic scenario of the Soyuz launch with Galileo satellites.
Payload section of the Soyuz-ST rocket with Galileo satellites. Credit: Arianespace
Galileo FOC-M9 satellites are integrated with their Fregat upper stage around Nov. 23, 2021. Click to enlarge. Credit: Arianespace
The payload section with 27th and 28th Galileo satellites is being integrated with the Soyuz launch vehicle. Click to enlarge. Credit: Arianespace
Artist rendering of the payload fairing separation during the launch of Galileo satellites. Click to enlarge. Credit: Arianespace
Artist rendering of the Galileo satellites separating from the Fregat upper stage. Click to enlarge. Credit: Arianespace
Initial ground track of the Soyuz launch with Galileo satellites. Click to enlarge. Credit: Arianespace
Around the time of the first Fregat burn, the vehicle will pass over a ground station in Santa Maria on Azores Island. Click to enlarge. Credit: Arianespace
After the first maneuver, Fregat and its passengers will climb passively toward an apogee of a transfer elliptical orbit over Russia and Asia. Click to enlarge. Credit: Arianespace
Around the time of the second maneuver to circularize the orbit, Fregat will pass over Nova Norcia ground station in Western Australia. Click to enlarge. Credit: Arianespace
Two Galileo satellites are scheduled to separate soon after completion of the Fregat's second maneuver. Click to enlarge. Credit: Arianespace
After the satellite release, Fregat is programmed to deactivate itself during the flight over the Pacific. Click to enlarge. Credit: Arianespace