In collaboration with Starsem and Roscosmos, Arianespace launched 34 new internet communication satellites aboard a Soyuz 2.1b for the OneWeb 9 mission. The flight marks the 8th operational launch of OneWeb satellites and brings the total number in orbit to 288: 48% of the 600 satellites required for global coverage with an additional 48 on-orbit spares for a total phase one constellation size of up to 648 satellites.
The launch was scheduled for Thursday, August 19; however, a rare scrub was called seconds before liftoff. A second attempt was first scheduled for Friday. Liftoff occurred on Saturday, August 21 from Site 31/6 at the Baikonur Cosmodrome in Kazakhstan at 22:13:40 UTC (18:13:40 EDT).
For this mission, the Soyuz 2.1b was equipped with a Fregat upper stage with a relightable engine that runs on unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (N2O4) and is capable of putting the 5,518 kg OneWeb payload into its roughly 450 km initial orbit at 84.7 degrees inclination.
OneWeb’s satellite constellation is a work-in-progress global internet and broadband platform similar to SpaceX’s Starlink and Amazon’s Project Kuiper. The goal of the constellation is to provide semi-low-latency internet to locations where ground-based internet is either not available or unreliable. Once complete, OneWeb will provide internet access with speeds up to 50 mb/s anywhere on the globe, including land, sea, and air.
After the first phase is complete, OneWeb will move onto phase two, which will consist of 6,372 satellites; this number was significantly decreased from the company’s previous proposal, which consisted of nearly 48,000 satellites.
Each OneWeb satellite has a mass of 147 kg and is equipped with a Ku-band antenna. The satellites were manufactured at OneWeb’s facility in Merritt Island, Florida, where they are produced in collaboration with Airbus Defense and Space. At this facility, OneWeb currently produces roughly two satellites per day, allowing for a theoretical maximum of nearly two launches per month.
Several weeks before launch, the 34 satellites were shipped to Kazakhstan where they were integrated onto the payload dispenser, which was manufactured by RUAG Space. The payload stack was then transferred to Arianespace and Starsem and integrated with the rocket.
Despite Soyuz being a Russian rocket manufactured by Roscosmos, Arianespace and Starsem handle the commercial sale and launch of the vehicle for OneWeb missions.
Four days before launch, on August 15, Arianespace conducted a launch readiness review (LRR) to ensure the launch vehicle and payload were ready for rollout and that the ground service equipment (GSE) and launch pad were ready to receive the Soyuz.
A day later, the vehicle rolled out to the launchpad, and GSE was hooked up. This process included connecting fueling quick disconnects, closing the launchpad servicing plate, conducting checks of GSE on the first, second, and third stages, and ensuring the payload was healthy.
Soyuz on the way to Site 31/6 during rollout operations for the OneWeb 9 mission. (Credit: Roscosmos)
Two days before the first launch attempt, teams conducted health checkouts of the Fregat fourth stage, which was fueled roughly two weeks prior.
Launch
The countdown began 5 hours 10 minutes before the scheduled liftoff. Forty minutes later, at T-4 hours 30 minutes, Soyuz began fueling with RP-1 kerosene and liquid oxygen.
At T-35 minutes, the servicing gantry clamshell was lowered to its launch position. Towards the end of the terminal count, two servicing arms pulled away from Soyuz, followed at T-16 seconds by the command to ignite the rocket’s four RD-107A engines, one on each booster, and the central RD-108A engine.
The four side boosters, known as the first stage, burned for 118 seconds and then separated in a pattern known as the Korolev Cross.
The core, known as the second stage, continued to burn until T+4 minutes 48 seconds.
The payload fairing, which protects the satellites from aerodynamic and thermodynamic loads during ascent, was jettisoned at T+3 minutes 38 seconds.
The third stage performed a “hot fire” separation from the second stage, meaning its single RD-0124 engine ignited while the stages were still attached. The third stage then burned for over four minutes.
(Video caption: How the Soyuz rockets light their engines. Credit: Scott Manley)
Following third stage shutdown, the Fregat stage ignited for a 5-minute long burn, putting the stage and payload into a parking orbit. Later, the Fregat stage will reignite to circularize the deployment orbit.
The RUAG Space-designed payload dispenser then deployed the 34 satellites over several hours. Between satellite separation events, the Fregat performed attitude corrections, ensuring that the payloads are deployed in the correct attitude.
The nominal mission duration for OneWeb 9 is 3 hours 45 minutes. Confirmation of successful deployment for all the satellites was confirmed by Roscosmos.
The OneWeb satellites will spend the coming months raising their orbits with their onboard Hall-effect thrusters to reach their final 1,200 km orbit.
Following final deployment, the Fregat stage performs a deorbit burn, ensuring the stage safely re-enters the Earth’s atmosphere.
(Lead image: The Soyuz performing its pitch and roll program after liftoff. Credit: Roscosmos)