Falcon 9 B1077-4 launched 56 Starlink v1.5 satellites into low Earth orbit on Wednesday, March 29 at 4:01 PM EDT (20:01 UTC), from SLC-40 at the Cape Canaveral Space Force Station.
The Falcon 9 flew on a southeast trajectory, as is usual during winter months to avoid recovery operations in rough seas to the northeast. The trajectory took the batch of Starlink satellites to an initial 299 by 339 km orbit inclined 43 degrees, with the deployment of the spacecraft occurring one hour and five minutes after liftoff.
While the second stage pushed the Starlink batch into orbit, the B1077 first stage landed 660 kilometers downrange on Just Read the Instructions (JRTI) in the Caribbean, near the Bahamas. This was the 182nd successful landing out of 193 attempts, counting drone ship and return to launch site landings.
B1077 has previously flown the Crew-5, GPS III-SV06, and Inmarsat I-6 F2 missions, and has also landed on JRTI twice before. The recovery ship Bob is also downrange and is tasked with recovering the fairings from this flight. The fairings, equipped with parachutes for a soft splashdown in the ocean, are now frequently reused, much like the first stages.
This flight marks the 20th Falcon 9 launch of 2023, as well as the 21st overall SpaceX launch, with up to 100 launches targeted for this year. To put this into perspective, in 2018 SpaceX launched 21 times in the entire year. This included the first flight of Falcon Heavy, as well as 20 Falcon 9 launches.
The 45th Weather Squadron of the US Space Force’s Space Launch Delta 45 forecasted only a 60 percent chance of acceptable weather during the launch opportunity. The main concerns were the thick cloud layer rule and liftoff winds, due to a front moving through the state Tuesday evening into Wednesday morning.
The weather outlook improved considerably for the backup day of Thursday, March 30, with an 85 percent chance of acceptable weather for launch. The only concern remaining as per the forecast would have been liftoff winds. In the end, acceptable weather materialized for the Wednesday window.
The 56 satellites, each massing approximately 307 kg, that were deployed on this flight will be moved to an operational circular orbit of 530 kilometers altitude over the coming months. They are part of the second generation constellation of the Starlink service, though these are still v1.5 satellites, not the “v2 Mini” spacecraft flown on Starlink Group 6-1 in late February 2023.
Though a new generation of Starlink satellites has started flying, it could take some time for the v2 satellites to fly in larger numbers. The first batch of v2 Mini satellites to fly has had teething problems, and as per Elon Musk some of these initial satellites will be deorbited while others will be further tested before going to an operational orbit.
In addition, the Starship launch vehicle that is planned to fly the full-size v2 satellites is still awaiting an FAA launch license as well as other preparations for its first orbital test flight. Even after Starship’s maiden flight, data analysis and other work would still be needed before these satellites start flying.
Further launches of the v1.5 satellite platform are still planned, while the next v2 Mini launch is set for no earlier than April.
After this launch, there have been 4,217 Starlink satellites launched into orbit, with at least 302 satellites no longer in orbit. The first operational Starlink launch took place in November 2019, and since then the service has been increasingly used for low-latency, high-speed broadband access in remote areas, disaster and war zones, and in aviation and marine settings.
Starlink has not been without its issues. Concerns have been raised regarding the brightness of these satellites and how they can impact astronomical observations, as well as the possibility of collisions with other satellites, generating space debris. Starlink currently has over one million active subscribers and an open waitlist for future users.
SpaceX has attempted to address the brightness concerns through various means, such as a failed dark coating and a more successful “sunshade,” though that had to be removed on v1.5 satellites due to the sunshade blocking inter-satellite laser links. Other brightness mitigation measures, such as dielectric mirror films, are still in work. The satellites also have an onboard autonomous collision avoidance system.
Up to 4,425 first-generation satellites were authorized for the Starlink constellation by the FCC in 2018. The second-generation (Gen2) constellation will be composed of nearly 30,000 second-generation satellites.
(Lead image: Falcon 9 lifts off from SLC-40 on the Starlink Group 5-10 mission. Credit: Julia Bergeron for NSF)