FAA Closes Starship OFT-2 Mishap Investigation

FAA Closes Starship OFT-2 Mishap Investigation

The FAA said today it has closed its mishap investigation of the second orbital flight test of SpaceX’s Starship, OFT-2, that took place last November. SpaceX must implement a set of corrective actions before the FAA will issue a license for OFT-3, but both the company and the FAA have indicated mid-March is a likely time frame.

Launched on November 18, 2023, OFT-2 got closer to reaching orbit than the first attempt seven months earlier, but fell short of its goal.

These Starship test flights will not actually make an orbit of the Earth, but go about three-quarters of the way around the globe eastward from SpaceX’s Starbase in Boca Chica, Texas to an ocean splashdown near Hawaii.

Starship is a two-stage rocket that stands 120 meters (394 feet) tall. Powered by 33 Raptor engines, the first stage is called Super Heavy. The second stage, with six Raptor engines, is called Starship. Confusingly, the combination of the two is also called Starship.

SpaceX’s Starship on the launch pad at Starbase in Boca Chica, TX in November 2023 prior to the second Orbital Flight Test, OFT-2 (also called an Integrated Flight Test or IFT). The silver first stage is called Super Heavy. The second stage, covered in black thermal protection tiles, is Starship, although the combination is also called Starship. Photo credit: SpaceX.

Although it didn’t reach orbit, OFT-2 did successfully demonstrate several changes SpaceX made after the first failure including “hot staging” where the second stage began firing its engines before detaching from the first stage to reduce the loss of velocity when the stages separate.

After the separation, however, the first stage exploded. The second stage didn’t attain orbit because they vented liquid oxygen and that led to a fire and an explosion. In a January 2024 update at Starbase, Musk pointed out they would not have vented the liquid oxygen if a payload had been aboard so “ironically if it had a payload, it would have reached orbit.”

Today, SpaceX provided more details. The first stage failed when “several engines began shutting down before one engine failed energetically, quickly cascading to a rapid unscheduled disassembly (RUD) of the booster” most likely because of “filter blockage where liquid oxygen is supplied to the engines.” The second stage flew nominally for seven minutes until liquid oxygen venting began and a “leak in the aft section … resulted in a combustion event and subsequent fires that led to a loss of communications” followed by “a commanded shut down of all six engines prior to completion of the ascent burn.” That triggered the flight termination system at an altitude of approximately 150 kilometers and a velocity of about 24,000 km/hour. The altitude made it the first Starship to reach space, even though it did not attain orbit.

The FAA is responsible for ensuring public safety, so the explosions of the first and second stages led to a mishap investigation.

In its statement today, the FAA said Space X must close seven corrective actions for the Super Heavy booster and 10 for Starship.

FAA Statement (February 26, 2024)

The FAA has closed the SpaceX-led mishap investigation of the Starship Super Heavy Orbital Test Flight 2 (OTF-2) launch that occurred on Nov. 18, 2023.

SpaceX identified, and the FAA accepts, the root causes and 17 corrective actions documented in SpaceX’s mishap report. Seven corrective actions were identified for the Super Heavy Booster including vehicle hardware redesigns, updated control system modelling, reevaluation of engine analyses based on OTF-2 flight data, and updated engine control algorithms. Ten corrective actions were identified for the Starship vehicle including vehicle hardware redesigns, operational changes, flammability analysis updates, installation of additional fire protection, and guidance and modelling updates.

The closure of the mishap investigation does not signal an immediate authorization of the next Starship launch.

Prior to the next launch, SpaceX must implement all corrective actions and receive a license modification from the FAA that addresses all safety, environmental and other applicable regulatory requirements. The FAA is evaluating SpaceX’s license modification request and expects SpaceX to submit additional required information before a final determination can be made.

Contact SpaceX for further information. Learn more about the FAA mishap program.

During the FAA’s Commercial Space Transportation conference last week in Washington, D.C., Nick Cummings, SpaceX Senior Director of Program Development, cited SpaceX Founder and Chief Engineer Elon Musk as saying the next Starship launch is targeted for the second week of March.

At a press availability later in the day, FAA Associate Administrator for Commercial Space Transportation Kelvin Coleman agreed that’s the time frame they are looking at for issuing the launch license: “That’s where I’m hearing things are headed right now.” He added they had been looking at the second week in February, but that slipped to “maybe mid-March.”

Coleman also revealed that SpaceX is looking at “up to nine launches this year” of Starship.

Musk and SpaceX are eager to get Starship working not only because it is critical for launching the company’s next-generation Starlink communications satellites, but it is under contract to NASA to use Starship as the Human Landing System (HLS) for the Artemis program. SpaceX needs to launch an uncrewed Starship test flight to land on the Moon prior to NASA’s Artemis III mission currently scheduled for September 2026.  NASA’s Space Launch System rocket and Orion spacecraft will take the astronauts to and from lunar orbit, but cannot put them on the surface. Orion will dock with a SpaceX Starship HLS in lunar orbit that will take the astronauts down to the surface and, six days later, back up where they will redock with Orion and return home. NASA is paying SpaceX $2.9 billion to develop the Starship HLS under a fixed-price contract.

Illustration of SpaceX’s Starship Human Landing System on the Moon. Note the astronauts at the base of the rocket for scale. Credit: SpaceX

There’s a lot of work to do before that.  As enormous as Starship is, it cannot go directly from the surface of Earth to the Moon like NASA’s Space Launch System. Instead, it must refuel at an as-yet nonexistent fuel depot in Earth orbit. The fuel depot itself will be a Starship and must be filled with fuel using other Starships. Various estimates exist of how many Starship launches are needed just to create and fill the depot for one flight to the Moon. In January 2024,  SpaceX’s Jessica Jensen, Vice President of Customer Operations and Integration, reluctantly said “it will roughly be 10-ish,” but could be more or less.


This article has been updated.

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