SpaceX to surpass 4,000 Starlink satellites on-orbit with Starlink Group 5-6


Lifting off from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Space Force Station in Florida, SpaceX’s 30th launch of 2023 will place 56 Starlink satellites into a low Earth orbit. Liftoff of the Starlink Group 5-6 mission is currently scheduled for May 4, 2023, at 03:31 AM EDT (07:31 UTC).

This mission will mark SpaceX’s 27th Falcon 9 flight of the year — alongside two Falcon Heavy flights and Starship’s maiden integrated flight test. The company has launched a rocket on average every ~4.2 days in 2023. Additionally, this launch will be SpaceX’s 157th Falcon 9 flight with a flight-proven booster.

SLC-40 supported the O3b mPOWER 3 & 4 mission just 5.39 days before the planned T0, marking the second fastest turnaround in SLC-40’s history. SpaceX is expected to break the 5.15-day turnaround record this month.

On May 2, the Space Launch Delta 45 released a launch mission execution forecast, giving the weather a 95% chance of being go for launch. The only concern for Thursday’s launch attempt is the cumulus cloud rule, which states that a launch cannot happen within 18.5 km of cumulus clouds with tops that extend into freezing temperatures. In the case of a delay, a backup launch window is set to open ~24 hours later, with the weather remaining at 95% go.

Following launch, SpaceX will attempt to land booster B1069-7 on its autonomous spaceport drone ship A Shortfall of Gravitas (ASOG), stationed 630 km downrange in the Atlantic Ocean. ASOG was tugged down range by Crosby Skipper. SpaceX’s multi-purpose recovery boat Bob will provide support for ASOG and recover the fairings from the water, just over 630 km downrange. If successful, this landing will mark SpaceX’s 189th successful landing and 115th consecutive landing.

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The booster supporting this flight, B1069-7, flew just 47 days ago and has supported CRS-24, Hotbird-13F, OneWeb Launch 15, SES-18 & 19, and two Starlink missions. Following B1052, B1053, and B1068 being expended on the ViaSat-3 Americas mission, B1069 is now one of 15 flight-proven boosters in SpaceX’s fleet. Upon successful landing, its designation will change to B1069-8.

Launching on Starlink Group 5-6 are 56 Starlink v1.5 satellites, which will be lofted into an initial orbit of 298 by 340 km inclined at 43.00 degrees. Following deployment, the satellites will raise their orbits into a Starlink second-generation orbit: a 530 km circular orbit at 43 degrees. With these satellites in orbit, SpaceX will surpass 4,000 satellites in orbit and will have launched 4,340 total satellites. 

Satellite Version


Sats Launched
Total in Orbit
Total Working

Group 1
550 km 53°

Group 2
570 km 70°

Group 3
560 km 97.6°

Group 4
540 km 53.2°

Group 5
530 km 43°

Group 6
2.0 Mini
530 km 43°

(Starlink information from Jonathan McDowell)

The now very-familiar Falcon 9 launch countdown sequence will start at T-38 minutes where the launch director will verify that all systems are go for propellant load. If the vehicle, ground service equipment, and teams are happy with the data, both the first stage and second stage will begin to be fueled with rocket propellant-1 (RP-1) at T-35 minutes. Also at this time, the first stage will begin being filled with liquid oxygen (LOX). 

The Falcon 9 launch vehicle uses super-chilled LOX, cooling it down to -205° C, which is significantly cooler than LOX’s -183° C boiling point. In fact, this temperature is not far below LOX’s freezing point of -219° C. Additionally, the RP-1 used on Falcon is also cooler than on other vehicles, with RP-1 being chilled to ~-10° C. By further chilling the propellants the density of each increases, thus increasing engine performance and mass of propellant on the vehicle.

At T-20 minutes, fueling on the second stage will complete and the transporter erector will begin purging its lines, preparing for stage two LOX load, which starts at T-16 minutes. This purging is what causes Falcon 9’s iconic T-20 minute vent (and Falcon Heavy’s T-22 minute vent). 

One minute before launch, the Falcon 9 will enter start-up and begin pressurizing its tanks for flight. This is when the vehicle takes command of the count; however manual aborts for technical reasons, weather, and range can still be called up until T-10 seconds. At this point, the vehicle is in full control of its countdown, and ground operators cannot abort the launch.

Falcon 9’s nine first stage engines right after liftoff. (Credit: SpaceX)

At T-3 seconds, the booster’s flight computer will command all nine Merlin 1D engines on the first stage to ignite in pairs, reducing transients on the first stage. Once the flight computer verifies that all engines and the vehicle are nominal, it will command for the hydraulic launch clamps to be released, allowing Falcon 9 to lift off.

The first stage, B1069, will burn for just under two and a half minutes before shutting down and separating from the second stage. Stage two will burn for approximately six minutes, while the booster completes its reentry and landing burns, landing on ASOG. During this time, the two fairing halves will be deployed at T+2:46, which will then utilize cold gas thrusters and parafoils to softly land in water for recovery.

The second stage will then coast for approximately 45 minutes before igniting its single Merlin Vacuum engine for two seconds. The stage will then coast for about 10 minutes, during which the stage will start to rotate end-over-end. The four tension rods will then be deployed at T+1:04:51, allowing all 56 Starlink satellites to deploy at once. 

This launch is SpaceX’s second launch of the month; if all goes to SpaceX’s plan, this will be the company’s busiest launch month ever with up to 10 launches. In support of this, there are back-to-back Starlink missions on May 8 from both coasts, followed later in the month by Arabsat 7B, Iridium-9, and other Starlink launches.

(Lead image: B1076 sitting on SLC-40 ahead of the Intelsat 40e mission. Credit: Max Evans for NSF)

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