Screenshot from SpaceX Webcast of the launch of OneWeb F15. A beautiful winter’s day. I’ll say
Mission Rundown: SpaceX Falcon 9 - OneWeb F15
Written: November 18, 2022 - Edit: December 9, 2022
Delivering a whole lot of boxes
SpaceX will be launching 40 OneWeb F15 satellites on their 55th mission of the year. The satellite stack weighing in at 4,500 kg (99,000 lb) will launch on a Falcon 9 rocket from Launch Complex 39A, Kennedy Launch Center in Florida, USA.
OneWeb Flight 15 will launch on Thursday, December 8, 2022 at 01:22:00 EDT, from SLC-40. The first stage booster B1069-4 will land on LZ-1 almost nine minutes after liftoff.
This launch was the first time a rocket achieved a polar inclination from LC-39A.
After boosting the second stage along with its payload towards orbit, the first stage will do a direct boost back burn before it performs a 30 second re-entry burn meant to slow the vehicle down before the atmospheric reentry. The booster will then perform a 27 second landing burn and softly land on Landing Zone 1 at CCSFS, Florida.
SpaceX will also recover both fairing halves in the Atlantic Ocean with the recovery vessel Doug, named after Demo-2 Astronaut Doug Hurley.
B1069-4 will have made its fourth flight after launching its next mission:
B1069-4 didn’t perform a static fire test after refurbishment while waiting for a west coast launch out of Vandenberg. SpaceX has since Starlink L08 omitted this safety precaution many times so far. It isn’t required to perform a static fire test on inhouse missions like Starlink as to save time.
SpaceX is the first entity ever that recovers and reflies its fairings. After being jettisoned, the two fairing halves will use cold gas thrusters to orientate themselves as they descend through the atmosphere. Once at a lower altitude, they will deploy drogue chutes and later a parafoil to help them glide down to a soft landing for recovery.
Falcon fairings halfs have been recovered and reused since 2019. Improved design changes and overall refurbishment procedures have decreased the effects of water landings and led to an increased recovery rate of fairings.
The fairings are an old pair flying on their fifth and sixth mission with no known joint mission. Both fairings are expected to survive the landing. Active fairings are equipped with four pushrods to separate the two fairing halfs.
Fairings have evenly spaced venting ports that have been redesigned a number of times by having first ten, then eight and now having their venting ports built as close pairs along the fairing edge. This prevents saltwater from the ocean from flooding and sinking the fairing, and makes refurbishment toward the next flight easier.
The OneWeb Payload
OneWeb Flight #15 was the first of three missions for OneWeb by SpaceX and marked OneWeb’s third overall mission in 2022. Additionally, this launch marked the third rocket OneWeb has flown on.
36 OneWeb satellites mounted on five ESPA rings on a Soyuz Fregat rocket from Roscosmos. link
SpaceX has room for four more in its fairing. The Sun-Synchronous Polar Orbit chosen by OneWeb is however straining the mission profile of Falcon 9 to its limits and the Return To Launch Site mission profile is straining it even more. Plus the 1st stage dogleg maneuver to avoid the populated coastal areas of Florida so it's stretched as thin it can be.
Airbus built the first set of satellites at their factory in France before the satellites’ primary production moved to Florida. OneWeb satellites are small, ~148 kg, and use electric propulsion to raise and keep their 1,200 km orbits. Twin solar panels power the spacecraft and its Ku-band antennas. With 40 satellites on Launch #15 – the most OneWeb satellites launched at once – the total mass on Falcon 9 is ~6,000 kg.
The first operational launch with 34 satellites took place a year after OneWeb Launch #1, on Feb. 6, 2020. OneWeb and Arianespace completed 12 more launches until Feb. 10, 2022, when the final launch with a Soyuz took place.
Launches on Soyuz halted and were abandoned shortly after the Russian invasion of Ukraine, when, shortly after, OneWeb signed launch contracts with SpaceX and India to launch its remaining satellites.
India launched the first of its two missions in October 2022 with 36 satellites. SpaceX will launch three missions, with its next scheduled for January 2023. Following Launch #15, OneWeb will have three more total launches before its initial constellation is complete.
The OneWeb 15 launch
Final launch preparations began at T-38 minutes, with an electronic go/no-go poll for propellant loading. Launch control started the auto sequence, allowing propellant loading to begin, at T-35 minutes with the first and second stages beginning RP-1 loading while LOX loading simultaneously started on the first stage.
Thirteen minutes later, stage two RP-1 loading was complete, with a purge of the T/E at T-20 minutes. At T-16 minutes, LOX loading began on stage two. At T-7 minutes, the Falcon 9 first stage chilled its engines with liquid oxygen to ensure there were no thermal shocks to the engines at ignition. The T/E retracted to the launch position at T-4 minutes 30 seconds.
Propellant loading was completed at T-2 minutes. Two significant events occurred simultaneously a minute later: the flight computer entered “startup,” and the propellant tanks pressurized to flight levels. The launch director gave the final “go” for launch 45 seconds before liftoff.
At T-3 seconds, the engine controller commanded the nine first-stage Merlin 1D engines to ignite. A second later, the engines ignited and began a final health check. Once the engines were verified healthy and producing full thrust, the hydraulic hold-down clamps and the T/E retracted, allowing the vehicle to lift off.
Shortly after liftoff, Falcon 9 pitched to follow the proper flight path to reach an 87.4-degree orbit. Initially, Falcon 9 pitched south-southeast and then completed a “dogleg” maneuver to the south to reach the proper azimuth for the desired orbit. The dogleg maneuver is needed to avoid overflight of populated areas on the Florida coast south of the space center.
After one minute and 12 seconds of flight, Falcon 9 reached maximum aerodynamic pressure (Max-Q).
After burning for two minutes and 17 seconds, the nine first-stage engines shut down. A few seconds later, the two stages separated. Second Engine Start (SES)-1 began just after stage separation. At the same time, the first stage began a flip maneuver to head back to LZ-1. After a near 180-degree rotation, the first stage ignited engines one, five, and nine for a 48-second burn back to LZ-1.
Six minutes and four seconds into the flight, the same three engines reignited for the entry burn, which lasted 17 seconds. The entry burn helped protect the stage from the forces caused by reentering Earth’s atmosphere.
Once the entry burn was complete, the first stage descended before reigniting engine nine one last time for the landing burn. The nearly 30-second burn allowed for a gentle landing on LZ-1. B1069-4 was redesignated B1069-5 at landing.
SpaceX will now move B1069 off of LZ-1 to refurbish the booster for a future mission.
While B1069 returned to LZ-1, the second stage continued to orbit. The payload fairing separated just over three minutes into the flight, exposing the 40 OneWeb satellites to space. The fairings were recovered ~604 km downrange by Doug.
Stage two burned until reaching an initial low Earth parking orbit. The second stage then coasted to apogee for a short and final four-second burn. In this final orbit, the OneWeb satellites separated from the payload adaptor in three sets over a span of just 32 minutes.
With this batch of satellites in orbit, the total number of OneWeb satellites in space stands at 504 of its initial 648 satellite target.
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