Falcon 9 · Vandenberg SFBStarlink Group 15-21

The launch vehicle is vertical on the pad. Ground crews perform final inspections, range safety checks, and verify all telemetry links. Weather balloons are launched to check upper-level winds.

RP-1 kerosene and liquid oxygen (LOX) are loaded into the first and second stages. LOX loading continues until just before launch due to boil-off. The strongback retracts to launch position.

Automated launch sequence begins. Flight computers take over countdown. Final range safety checks, propellant pressurization, and engine chill procedures are completed. Launch director polls all stations for GO.

Nine Merlin 1D engines ignite generating 1.7 million pounds of thrust. The vehicle is released from hold-down clamps at T+0 and begins its ascent. The vehicle clears the tower within seconds.

The vehicle passes through the region of maximum aerodynamic stress at approximately 35 kPa. Engines throttle down to ~70% to reduce structural loads, then throttle back up after passing through Max-Q.

All nine first-stage engines shut down after accelerating the vehicle to approximately 2.3 km/s. The first stage has burned through most of its propellant. Brief coast phase begins before stage separation.

Pneumatic pushers separate the first and second stages. Cold gas thrusters orient the first stage for its return journey. The interstage separates cleanly, allowing the second stage engine to ignite safely.

The single Merlin Vacuum engine ignites in the near-vacuum of space. Its extended nozzle is optimized for vacuum operation, producing 981 kN of thrust. This burn will place the payload into its target orbit.

The two halves of the payload fairing separate and fall away, exposing the payload to space. The fairing is no longer needed as the vehicle is above the sensible atmosphere. Fairings may be recovered by ships at sea.

The second stage engine shuts down after achieving the target orbital velocity of approximately 7.8 km/s. The payload is now in its target orbit at approximately 250 km altitude.

The payload separates from the second stage adapter. Springs or motorized mechanisms push the satellite away from the rocket. The satellite deploys solar panels and begins its own mission.

The first stage performs a series of burns: boostback burn to reverse trajectory, entry burn to slow down through the atmosphere, and a single-engine landing burn. Grid fins steer the booster to a precision landing on a drone ship or landing pad.

All primary mission objectives have been achieved. The payload is confirmed in its target orbit with healthy telemetry. The first stage has been recovered (if applicable). Mission success declared.