Iridium-9 & OneWeb 19 | Falcon 9 Block 5

Lift Off Time
(Subject to change)
May 19, 2023 – 13:19 UTC | 09:19 EDT
Mission Name
Iridium-9 & OneWeb 19
Launch Provider
(What rocket company is launching it?)
(Who’s paying for this?)
Iridium and OneWeb

Falcon 9 Block 5 B1063-11; 34.27-day turnaround
Launch Location
Space Launch Complex 4E (SLC-4E), Vandenberg Space Force Base, California, USA
Payload mass
~7,000 kg (~15,500 lb) (Iridium: 5 x 4,800 k8; OneWeb: 16 x 147.7 kg plus deploy hardware)
Where are the satellites going?
Polar low-Earth orbit
Will they be attempting to recover the first stage?
Where will the first stage land?
The booster will land ~600 km downrange on Of Course I Still Love You
Will they be attempting to recover the fairings?
Yes, the fairings will be recovered by GO Beyond
Are these fairings new?
How’s the weather?
The 30th weather squadron does not release public weather forecasts
This will be the:
– 225th Falcon 9 launch
– 161st Falcon 9 flight with a flight-proven booster
– 167th re-flight of a booster
– 33rd re-flight of a booster in 2023
– 193rd booster landing
– 119th consecutive landing (a record)
– 34th launch for SpaceX in 2023
– 42nd SpaceX launch from 
– 72nd orbital launch attempt of 2023
Where to watch
The official livestream will be listed here once available

What’s All This Mean?

SpaceX is set to launch 15 OneWeb internet communication satellites (and a single test satellite) atop its Falcon 9 Block 5 rocket. Alongside these satellites, Iridium will launch five of its Iridium-9 next-generation satellites. Lifting off from Space Launch Complex 4 East, at Vandenberg Space Force Base, in California, USA, this mission will place satellites into a polar orbit.

This mission will be the second mission of SpaceX’s second-stage Merlin vacuum nozzle redesign, which is only used on lower-performance missions. This shorter, and therefore lower-performance, nozzle decreases the number of return to launch site (RTLS) missions that SpaceX is able to launch; for this reason, this mission is landing on one of SpaceX’s drone ships.

What Is Iridium’s Constellation?

The Iridium-9 satellites will enhance Iridium’s current constellation, which was largely launched by SpaceX between 2017 and 2019, and replace several satellites. The constellation has 66 operational satellites, nine on-orbit spares, and six spares on the ground.

Iridium’s constellation provides L-band voice and data to satellite phones across the globe. The satellites are placed in a low-Earth orbit at 781 km and inclined at 86.4º–this near-polar orbit is what allows for them to cover the entire globe. Each satellite has a launch mass of 689 kg and has two deployable solar panels and batteries.

What Is OneWeb?

OneWeb is a planned satellite internet constellation with the goal of providing internet coverage to the entire globe. Similar to SpaceX’s Starlink, the OneWeb constellation aims to deliver semi-low-latency internet to locations where ground-based internet is unreliable or unavailable.

OneWeb plans to have 648 satellites in its constellation, providing them with the 600 satellites needed for global coverage and an additional 48 on-orbit spares in case a satellite fails. These satellites are in a 1,200 km low-Earth polar orbit, which is significantly lower than the global internet services available today. The current satellite internet solutions orbit 35,786 km above the Earth, in geostationary orbit. However, the orbit of OneWeb’s satellites is still significantly higher than the ~550 km orbit that SpaceX’s Starlink satellites use. OneWeb is expecting the final 648 satellite constellation to provide download speeds of roughly 50 Mb/s.

OneWeb. orbits
Final orbits of the 648 satellite constellation (Credit: Airbus)

The constellation consists of 18 orbital planes, with 36 satellites in each plane. However, in May 2020, OneWeb submitted an application to the FCC, requesting to increase its constellation size to 48,000 satellites. OneWeb has also announced that the second generation of the OneWeb network will be a global navigation satellite system (GNSS), like GPS.

What Is A OneWeb Satellite?

Each OneWeb satellite has a compact design and a mass of 147.5 kg. The satellites are each equipped with a Ku-band antenna, operating between 12 and 18 GHz. One interesting note is that these satellites will use a slightly abnormal frequency, eliminating interference with satellites in geostationary orbit.

The OneWeb satellites were built by OneWeb Satellites, which is a joint venture between OneWeb and Airbus.

The satellites are designed to deorbit after 25 years safely. However, this leaves many concerned as this orbital region is already the most crowded with space debris.

OneWeb, satellite
Artist depiction of a OneWeb satellite (Credit: TechCrunch)

OneWeb’s Return

In March 2020, OneWeb filed for Chapter 11 bankruptcy and laid off most of its employees. However, OneWeb was able to maintain operations for the 74 satellites they currently had in orbit. In November 2020, the UK government and Bharti Enterprises invested over a billion US dollars into OneWeb with the goal of finishing the constellation.

As if these issues weren’t enough, in wake of new European sanctions at the start of the year OneWeb was unable to launch their satellites on the Soyuz vehicle–the rocket that launched the first 13 OneWeb missions. In lieu of this, on April 20, 2022, OneWeb announced launches atop the GSLV Mk III and Falcon 9.

What Is Falcon 9 Block 5?

The Falcon 9 Block 5 is SpaceX’s partially reusable two-stage medium-lift launch vehicle. The vehicle consists of a reusable first stage, an expendable second stage, and, when in payload configuration, a pair of reusable fairing halves.

First Stage

The Falcon 9 first stage contains 9 Merlin 1D+ sea-level engines. Each engine uses an open gas generator cycle and runs on RP-1 and liquid oxygen (LOx). Each engine produces 845 kN of thrust at sea level, with a specific impulse (ISP) of 285 seconds, and 934 kN in a vacuum with an ISP of 313 seconds. Due to the powerful nature of the engine, and the large amount of them, the Falcon 9 first stage is able to lose an engine right off the pad, or up to two later in flight, and be able to successfully place the payload into orbit.

The Merlin engines are ignited by triethylaluminum and triethylborane (TEA-TEB), which instantaneously burst into flames when mixed in the presence of oxygen. During static fire and launch the TEA-TEB is provided by the ground service equipment. However, as the Falcon 9 first stage is able to propulsively land, three of the Merlin engines (E1, E5, and E9) contain TEA-TEB canisters to relight for the boost back, reentry, and landing burns.

Second Stage

The Falcon 9 second stage is the only expendable part of the Falcon 9. It contains a singular MVacD engine that produces 992 kN of thrust and an ISP of 348 seconds. The second stage is capable of doing several burns, allowing the Falcon 9 to put payloads in several different orbits.

For missions with many burns and/or long coasts between burns, the second stage is able to be equipped with a mission extension package. When the second stage has this package it has a grey strip, which helps keep the RP-1 warm, an increased number of composite-overwrapped pressure vessels (COPVs) for pressurization control, and additional TEA-TEB.

falcon 9 block 5, launch
Falcon 9 Block 5 launching on the Starlink V1.0 L27 mission (Credit: SpaceX)

Falcon 9 Booster

The booster supporting this mission is B1063-11. As the name implies, the booster has supported 10 previous missions.

B1063’s missionsLaunch Date (UTC)Turnaround Time (Days)
Sentinel-6November 21, 2020 17:17N/A
Starlink V1.0 L28May 26, 2021 18:59186.07
DARTNovember 24, 2021 06:21181.47
Starlink Group 4-11February 25, 2022 17:1262.45
Starlink Group 4-13May 13, 2022 22:07108.20
Starlink Group 3-1July 11, 2022 01:3958.15
Starlink Group 3-4August 31, 2022 05:4051.17
Starlink Group 4-31October 28, 2022 01:1457.82
Starlink Group 2-5February 17, 2023 19:12112.75
Transporter-7April 15, 2023 6:48 UTC56.48
Iridium-9 and OneWeb 19May 19, 2023 13:1934.27

Following launch, the Falcon 9 booster will conduct two burns. These burns aim to softly touch down the booster on Of Course I Still Love You.

falcon 9 booster, landing, drone ship
Falcon 9 landing on Of Course I Still Love You after launching Bob and Doug (Credit: SpaceX)

Falcon 9 Fairings

The Falcon 9’s fairing consists of two dissimilar reusable halves. The first half (the half that faces away from the transport erector) is called the active half, and houses the pneumatics for the separation system. The other fairing half is called the passive half. As the name implies, this half plays a purely passive role in the fairing separation process, as it relies on the pneumatics from the active half.

Both fairing halves are equipped with cold gas thrusters and a parafoil which are used to softly touch down the fairing half in the ocean. SpaceX used to attempt to catch the fairing halves, however, at the end of 2020 this program was canceled due to safety risks and a low success rate. On Iridium-9 and OneWeb 19, SpaceX will attempt to recover the fairing halves from the water with its recovery vessel GO Beyond.

In 2021, SpaceX started flying a new version of the Falcon 9 fairing. The new “upgraded” version has vents only at the top of each fairing half, by the gap between the halves, whereas the old version had vents placed spread equidistantly around the base of the fairing. Moving the vents decreases the chance of water getting into the fairing, making the chance of a successful scoop significantly higher.

All times are approximate

00:38:00SpaceX Launch Director verifies go for propellant load
00:35:00RP-1 (rocket grade kerosene) loading underway
00:35:001st stage LOX (liquid oxygen) loading underway
00:16:002nd stage LOX loading underway
00:07:00Falcon 9 begins engine chill prior to launch
00:01:00Command flight computer to begin final prelaunch checks
00:01:00Propellant tank pressurization to flight pressure begins
00:00:45SpaceX Launch Director verifies go for launch
00:00:03Engine controller commands engine ignition sequence to start
00:00:00Falcon 9 liftoff

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