On Monday, SpaceX conducted the first of two Starlink launches this week from each coast of the United States. The first was the launch of the Starlink Group 6-1 mission at 6:13 PM EST (23:13 UTC) from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Space Force Station in Florida.
The Starlink Group 6-1 mission was the first to carry Starlink’s next-generation satellite version, Starlink v2. SpaceX started launches in support of Starlink’s second generation constellation, Starlink Gen 2, back in December 2022 with the Group 5 missions. However, these have been carried out by launching Starlink v1.5 satellites instead of the upgraded Starlink v2 satellites making the debut on this mission.
Another batch of v1.5 satellites then lifted off on Friday as part of the Group 2-7 mission. Launch from SLC-4E at the Vandenberg Space Force Base in California occurred at 10:38 AM PST (18:38 UTC).
Group 6-1 Mission Profile
The Falcon 9 countdown was the traditional 35-minute long propellant load sequence which begins with RP-1 (a refined form of kerosene) load on both stages and liquid oxygen (LOX) load on the first stage.
Loading of RP-1 on the second stage wraps up at the T-20 minute mark followed by the usual “T-20 minute vent” as purging begins on the lines of the Falcon 9 Transporter/Erector (T/E) that supplies fluids and power to the vehicle. LOX load on the second stage begins about four minutes after that at T-16 minutes.
Engine chill commences at the T-7 minute mark with a small flow of LOX going into the turbopumps on all nine Merlin engines on the first stage. RP-1 load on the booster then wraps up about a minute later.
LOX load on the first and second stages ends at around the T-3 minute and T-2 minute mark respectively, and the rocket takes control of the countdown at the T-1 minute mark.
Engine ignition is commanded at T-3 seconds and if engine checks look correct, the ground clamps release the rocket for liftoff at the expected T0 time.
The flight profile of Falcon 9 on Monday was similar to the one seen on Group 5 missions with the rocket arching to the southeast on its path to orbit. The first stage for this mission, B1076, was flying for a third time, having previously supported the CRS-26 and OneWeb-16 missions. It fired its engines for about two and a half minutes and then separated from the second stage.
The booster then performed its usual entry and landing burns for a landing on SpaceX’s Autonomous Spaceport Drone Ship A Shortfall Of Gravitas which was located approximately 636 km downrange.
After stage separation, the second stage fired its single Merlin 1D Vacuum (MVac) engine for about six minutes to inject the satellites into a parking orbit. The fairing halves separated approximately 10 seconds into MVac’s first burn. The fairing halves fall to a parachute-assisted splashdown in the Atlantic Ocean to be recovered by SpaceX’s multi-purpose recovery vessel Doug.
LHA map for #Starlink Group 6-1 from CCSFS SLC-40 NET 23 Feb 18:37 UTC, altern. 24 Feb to 01 Mar based on NOTAM/NOTMARs. B1076.3 planned landing with estimated fairing recovery ~637km downrange. Final inclination 43°. S2 reentry area south of Cape Town. https://t.co/8FuSogeAaR pic.twitter.com/7kqJFp6xZP
— Raul (@Raul74Cz) February 22, 2023
Once in orbit, the second stage coasted for about 46 minutes to apogee and then performed a second MVac burn to circularize the orbit. After another coast phase, the satellites were released into a 365 by 373-kilometer orbit at 43 degrees inclination. Here they’ll be checked out and if they’re operating nominally, they will then raise their orbits to operational altitudes which should happen in a few weeks or months. Soon after satellite deployment, the second stage performs a deorbit burn for disposal over the western Indian Ocean.
This mission is launching 21 Starlink v2 satellites into the 43-degree inclination shell of Starlink Gen 2. However, these Starlink v2 satellites are not of the same design as the Starlink v2 satellites designed for launch on SpaceX’s Starship rocket.
We call them “V2 Mini”. They represent a step forward in Starlink capability pic.twitter.com/EFVpLFcz7n
— SpaceX (@SpaceX) February 26, 2023
The answer as to what type of satellite they would launch and how the satellites would be deployed for Starlink Gen 2 has been changing ever since SpaceX proposed it back in May 2020.
Back then the assumption was that the satellites would be of similar size and mass to the ones launched during that time with minor upgrades to support the E-band frequency added to this constellation.
The question remained as to how these would be deployed with comments from SpaceX’s President Gwynne Shotwell claiming that hundreds of these could eventually be flown on Starship. However, Starship was still very early in its prototype phase which indicated that SpaceX likely didn’t have a firm plan yet for deploying this constellation.
In August 2021 SpaceX amended their Starlink Gen 2 proposal to include two configurations of the constellation with different orbital shells and distributions of the satellites around the globe. One configuration would use Starship for the deployment of the satellites and the other would use Falcon 9. The first configuration was planned to be the primary while the other was only proposed as a backup in case of delays to Starship’s development.
The same amendment claimed that the satellites in support of Starlink Gen 2 would “be somewhat larger and generate more power, enabling them to support expanded capabilities now and accommodate additional payloads in the future”. This indicated a further revision to Starlink’s satellite design would debut for this new constellation.
In December 2021, the Federal Communications Commission (FCC) sent a letter to SpaceX with a series of questions concerning the amendment to their Starlink Gen 2 proposal to which SpaceX replied a month later.
NASASpaceflight went into the details of the letter but the key takeaway from it was that now the company had abandoned the two-configuration approach. Instead, SpaceX was planning to launch the Starlink Gen 2 satellites with Starship rather than using Falcon 9. This was further confirmed by Elon Musk a few months later in an interview with Tim Dodd where the company CEO mentioned that the Starlink v2 satellites would have a mass of about 1250 kg and be 7 m in length.
The larger mass and size meant that the satellites would not be able to fit in a Falcon 9 fairing and therefore launching these Starlink v2 satellites on Falcon 9 was very unlikely.
However, in another change of plans from SpaceX, the company announced to the FCC in August 2022 that they were now planning to also leverage Falcon 9 to deploy the constellation. This was a result of the continued delays with Starship’s development that would necessitate additional launch capability. SpaceX would develop and use downsized Starlink v2 satellites that could fit in Falcon 9’s fairing but with the same technologies as the Starlink v2 satellites to be used on Starship.
Later that month, Elon Musk confirmed at a joint event with T-Mobile that these satellites would be colloquially referred to as “Starlink v2 Mini” as they would be smaller but still heavily based on the Starlink v2 satellite design.
Monday’s launch will deploy this downsized version of Starlink v2 satellites with 21 of them riding inside the Falcon 9 fairing, less than half the number of satellites that the company has been launching on each mission with the earlier Starlink v1.5 design. This puts the mass of each satellite between 750 kg and 800 kg which is more than twice the mass of the Starlink v1.5 satellites and more than half the mass of the full-size Starlink v2 satellite to be launched on Starship.
Before the launch, SpaceX also shared more updates on Twitter about Starlink v2’s design compared to the design of Starlink v1.5 satellites. The company explained that these satellites can provide four times more capacity than the earlier satellites so even though there are almost three times fewer satellites per launch compared to Starlink v1.5 launches, every launch with Starlink v2 Mini satellites will introduce more capacity overall into the system.
Among other enhancements, V2 minis are equipped with new argon Hall thrusters for on orbit maneuvering pic.twitter.com/4G5nI3zsyX
— SpaceX (@SpaceX) February 26, 2023
These new Starlink v2 Mini satellites also introduce a new propellant of choice for the Hall Effect thrusters that the satellites use, changing from Krypton to Argon. SpaceX started using Krypton ever since the launch of Starlink v0.9 satellites back in May 2019 and the most likely reasons for using this fuel instead of the more traditionally used Xenon gas could have been the lower cost and higher availability.
The choice of Argon with Starlink v2 could be also oriented with that same thinking. Argon is the third most common gas in the atmosphere so it is very accessible and very cheap. Another potential reason for this use could also be related to the current geopolitical situation with the Russian invasion of Ukraine since the latter is a heavy producer of Krypton in the world. SpaceX claims these new Argon thrusters produce 2.4 times greater thrust and have 1.5 times greater specific impulse.
This mission is launching these satellites into the same 43-degree orbital inclination shell as the Group 5 launches. More Group 5 and Group 6 launches are set to come in the next weeks and months, indicating that SpaceX may be mixing the satellite versions used in this particular shell rather than deploying the new satellites into a different shell.
While Starlink v2 launches are now starting, this doesn’t mean SpaceX has stopped the deployment of Starlink v1.5 satellites. The second Starlink launch of the week lofted 51 Starlink v1.5 satellites to low Earth orbit (LEO) from SpaceX’s launch site at Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California.
Liftoff occurred at 10:38 PM PST (18:38 UTC) on Friday. The launch from Vandenberg featured booster B1061 flying on its 12th mission. It successfully landed on SpaceX’s Autonomous Spaceport Drone Ship Of Course I Still Love You which was located 660 km southeast in the Pacific Ocean. The fairing halves also splashed down in the Pacific Ocean with fairing recovery ship NRC Quest tasked with their recovery.
The second stage performed a single burn to inject the 51 Starlink satellites into their target orbit and then deployed them. It’ll perform another burn after deployment for disposal over the eastern Pacific Ocean. The satellites, which are headed to the second shell of Starlink’s first-generation constellation, will then raise their orbits as they’re checked out and phased into their operational orbits.
With these two launches, SpaceX will have launched 3,814 satellites in support of Starlink’s first generation constellation and 239 satellites for Starlink Gen 2 for a total of 4,053 satellites overall. Of these, 298 satellites have reentered and 3,194 satellites are in operational orbits.
(Lead photo: Falcon 9 launches the Starlink 2-7 mission. Credit: SpaceX)