On March 26, 2024, the FAA (Federal Aviation Administration) of the United States announced that it had closed its investigation into the second flight of the starship. The investigation was a mandatory requirement because the vehicle was destroyed during launch, and its closure paves the way for a third mission that could take place in mid-March. It should be clarified that SpaceX is actually conducting the investigation and it is the FAA that decides whether or not to accept the results, plus SpaceX conducted a separate investigation for the B9 Superheavy and another for the S25 Starship. The second flight of the starship is designated OFT-2 (Orbital Flight Test 2) in research instead of IFT-2 (Integrated flight test 2), although both names were used throughout these months (technically it was not an orbital mission, as the starship was to be placed on a suborbital trajectory, but the difference in energy expression is almost negligible). Thanks to a note from the FAA and an update on the SpaceX site when the news broke, we can now confirm exactly what happened on that mission.
On November 18, 2023, at 13:02 UTC, a group consisting of Super Heavy B9 (Booster 9) and spacecraft S25 (Starship 25) launched from Starbase (Boca Chica, Texas). The Raptor B9’s 33 engines performed perfectly, indicating the proper functioning of the Electric Thrust Control (TVC) system, which was tested for the first time on this mission. When the moment of separation occurred, the B9 was separated from the S25 by hot separation, that is, the S25 engines were turned on while the three central B9 Raptors were still on (remember that this launch also tested for the first time the design of a hot separation ring inserted between the two degrees). Just after separation, the Super Heavy had to use 13 engines to perform a refueling (in this case it would not return to the launch pad, but to a point near the coast). During the 180º turn maneuver several engines shut down and shortly thereafter one of the Raptors experienced a “power failure” (another nice euphemism for “explosion”). The B9 as a whole then exploded and disintegrated at an altitude of 90 kilometers. So it is officially confirmed that as it was already Voice of people The FTS destruction system has been operating for several months (Flight termination system) from B9 did not activate.
According to SpaceX, the most likely cause of the B9 breakup was that a filter in the liquid oxygen supply clogged, causing a pressure drop in the oxygen turbopumps that caused one of the engines to explode due to the difference in propellant pressures. This explosion subsequently caused a series of damages that ended with the explosion of B9. The filter was certainly blocked by some piece of the B9’s interior that came loose during the reentry maneuver, although SpaceX and the FAA are not providing more details at this time, nor are they specifying why the other B9 engines except the one that shut down.exploded (they also shut down due to a blockage oxygen filter?).
The S25 continued into space with all six Raptor engines running smoothly. As planned, after 7 minutes and 5 seconds of the mission, the leakage of liquid oxygen began to compensate for the absence of a payload (the S25 carried a lot of liquid oxygen to simulate the behavior of the vehicle with a cargo, which is why the engineers at SpaceX decided to expel the excess to have on return adequate mass into the atmosphere). An oxygen leak caused a leak in the back of the ship, resulting in a fire and loss of communication between the S25 computer in the front and the computer in the back. As a result of this problem, six Raptors were ordered to shut down and the FTS was activated according to its programmed parameters, destroying the ship at an altitude of 150 kilometers and at a speed of 24,000 km/h. As a consolation, S25 made history as the first starship to officially reach space.
The FAA has indicated to SpaceX seven corrective actions for the Super Heavy and ten for the Starship that it must implement for the next flight. The measures already applied to the B10/S28 assembly should serve to reduce fuel leaks, improve engine management analysis and increase fire protection. Improvements to the propellant filters and new panels were also added to reduce fluid movement in the B9 tanks during separation. More specifically, it is believed that a splash of liquid oxygen in a tank located at the base of B9 may have caused severe damage to the Super Heavy, ending up destroying it.
Now the FAA must grant SpaceX a launch clearance modification for the third mission, which will surely arrive in the next few weeks in time for the B10/S28 liftoff (the kit, on the other hand, has already had two failed attempts to perform a WDR fuel tank test). But leaving aside what will happen with this specific set, it’s worth remembering that SpaceX plans to launch nine (9!) Starships over the course of 2024.
