What is the planned sequence of Super Heavy Booster once it is decided that tower catch is not feasible?

 When automated safety checks or mission criteria determine that a Mechazilla tower catch is not feasible, SpaceX's Super Heavy booster executes a pre-planned offshore diversion sequence ending in a controlled water landing in the Gulf of Mexico rather than returning to the Starbase launch mount.

1. Automated Health Checks and Abort Trigger: Throughout ascent, boostback, and descent, onboard flight computers and ground systems continuously monitor critical booster telemetry—such as position, velocity, and engine health—alongside launch tower hardware status. If any required parameter falls outside safe catch limits, an automatic abort is triggered (or a manual "no-go" is commanded) to protect the launch complex from potential impact damage.
   
   
2. Offshore Trajectory Diversion: Depending on when the abort occurs, the booster either maintains an initial offshore return trajectory following hot-staging and boostback, or executes a pre-planned divert maneuver away from Starbase during final descent. This steers the vehicle into a designated marine exclusion zone in the Gulf of Mexico.
   
   
3. Controlled Descent and Landing Burn: Rather than shutting down early, the booster flies a full simulated catch profile over open water. It uses its grid fins for aerodynamic guidance before re-igniting its Raptor engines for a landing burn to decelerate the stage.
   
   
4. Hover and Soft Splashdown: At the conclusion of the landing burn, the booster slows to a near-hover just above the ocean surface—replicating the final alignment phase between the tower's chopstick arms—before executing a soft splashdown.
   
   
5. Post-Splashdown Safing: Once the simulated landing is completed, the booster tips over or undergoes safing and termination procedures (such as Flight Termination System activation or structural venting) in the offshore debris zone, where support vessels monitor the site.

Here is what occurred with Booster 22 during Starship Flight 15 on November 13, 2026. Each step in that sequence reflects SpaceX's autonomous fault-protection logic working as intended to protect Orbital Launch Pad 2 at Starbase:

• Autonomous "Plan B" Catch Abort (GNC Anomaly): Booster 22—a Block 3 Super Heavy vehicle—was initially cleared for a return-to-launch-site catch. During return flight, after 27 of 28 boostback engines relit, the booster's onboard flight computers detected a Guidance, Navigation, and Control (GNC) anomaly. SpaceX spokesperson confirmed during the live broadcast that the fault originated on the booster side rather than the launch tower, causing the vehicle to automatically call off the catch attempt.
  
  
• Controlled Offshore Divert and Landing Burn: Because the booster could not guarantee the pinpoint positional and attitude accuracy required to thread between the tower's chopstick arms, it executed its pre-programmed offshore divert into a cleared marine zone in the Gulf of Mexico. Even in abort mode, Super Heavy flies a complete simulated catch trajectory—guiding itself down with its grid fins and firing its Raptor engines to decelerate to a near-hover just above the ocean surface.
  
  
• Post-Cutoff FTS Activation and Fireball: Immediately after the landing burn engines shut down a short distance above the water, the Flight Termination System (FTS) triggered. Linear shaped charges ruptured the stainless-steel propellant tanks, causing the remaining liquid methane and liquid oxygen to mix and ignite in a bright aerial fireball before the stage struck the sea. Firing the FTS right after engine cutoff safely consumes residual propellants and neutralizes the live FTS ordnance in mid-air rather than leaving a pressurized, volatile hull floating in shipping lanes or breaking up unpredictably on wave impact.
  
  
• No Water Recovery Capability: Unlike Falcon 9 boosters—which carry deployable landing legs and can occasionally survive a gentle ocean touchdown intact enough to be towed—Super Heavy has no landing legs or marine recovery hardware. Structurally, it is engineered solely to be suspended by its forward catch pins on the launch tower arms, making any offshore diversion an expendable telemetry-gathering contingency.

Super Heavy booster has waffle-patterned grid fins mounted near its top (just below the open hot-staging interstage), which look and function differently from the solid aerodynamic flaps on the upper-stage Starship.

• Grid Fins (Booster) vs. Body Flaps (Ship): The upper-stage Starship uses four large, hinged, solid-panel flaps (two near the nose cone and two near the engines) to glide horizontally through the atmosphere. By contrast, the Super Heavy booster descends vertically—engines down—and uses open-lattice grid fins near the top that rotate to steer the booster toward the catch tower or offshore abort zone.

• Booster 22's Redesigned Three-Fin Layout: Earlier Block 1 and Block 2 boosters had four grid fins, whereas Block 3 boosters like Booster 22 were redesigned with three asymmetrically spaced grid fins. Each fin is roughly 50% larger and stronger than previous versions, and houses the structural catch points that allow Mechazilla's chopstick arms to lift and catch the booster directly by the fins.