Starship Flight Test 3 Moves One Step Closer

SpaceX's Starship/Super Heavy Flight Test 3 moved closer in concept on Monday as the FAA closed its investigation of November's IFT-2.  A first date estimate would be in the second half of March, between the 17th and 31st (Easter). 

"SpaceX identified, and the FAA accepts, the root causes and 17 corrective actions documented in SpaceX’s mishap report," the federal agency said in a statement issued Monday. "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."

SpaceX must still submit additional information to the FAA, which is responsible for the safety of people and property on the ground, before the agency completes its review of an application to launch Starship for a third time. The administrator for Commercial Space Transportation at the Federal Aviation Administration, Kelvin Coleman, said last week that early to mid-March is a reasonable timeline for the regulatory process to conclude.

I heard or read somewhere that the last flight was three weeks after the equivalent approval for that one, so we can figure two weeks later for this one.  Which is how the two week window I mentioned at the top was derived.  

SpaceX posted a summary of the technical findings they sent to the FAA on their Updates web page.  In big-picture overview, both the Super Heavy first stage and the Starship upper stage performed well except for a couple of problems that led to the loss of both parts of the vehicle.  

In the Super Heavy's case, the launch and flight through stage separation was flawless.  SpaceX describes it this way:

Following stage separation, Super Heavy initiated its boostback burn, which sends commands to 13 of the vehicle’s 33 Raptor engines to propel the rocket toward its intended landing location. During this burn, several engines began shutting down before one engine failed energetically, quickly cascading to a rapid unscheduled disassembly (RUD) of the booster.

"Failed energetically?" Cascading to a RUD?"  Love it!  You guys have been in Texas long enough to say, "It Done Blowed Up" or just "it blowed up."  The problem was linked to a problem with the liquid oxygen flow in the booster.  

The most likely root cause for the booster RUD was determined to be filter blockage where liquid oxygen is supplied to the engines, leading to a loss of inlet pressure in engine oxidizer turbopumps that eventually resulted in one engine failing in a way that resulted in loss of the vehicle. SpaceX has since implemented hardware changes inside future booster oxidizer tanks to improve propellant filtration capabilities and refined operations to increase reliability.

The six engines on Starship had ignited and burned completely nominally until what appears to have been an operational mistake over the Caribbean.  In an effort to simulate the extra fuel load required for some missions, they overfilled Starship with liquid oxygen, and decided they'd dump that extra LOX out there.  

A leak in the aft section of the spacecraft that developed when the liquid oxygen vent was initiated resulted in a combustion event and subsequent fires that led to a loss of communication between the spacecraft’s flight computers. This resulted in a commanded shut down of all six engines prior to completion of the ascent burn, followed by the Autonomous Flight Safety System detecting a mission rule violation and activating the flight termination system, leading to vehicle breakup. The flight test’s conclusion came when the spacecraft was as at an altitude of ~150 km and a velocity of ~24,000 km/h, becoming the first Starship to reach outer space.

SpaceX has implemented hardware changes on upcoming Starship vehicles to improve leak reduction, fire protection, and refined operations associated with the propellant vent to increase reliability. The previously planned move from a hydraulic steering system for the vehicle’s Raptor engines to an entirely electric system also removes potential sources of flammability.

The LOX didn't need to be released over the Caribbean, it just had to be dumped before the planned splashdown north of Hawaii. They could have released it later. Or, maybe, instead of LOX they could have put an equivalent weight of steel on the Starship?

Starship launches on its second flight on November 18, 2023.  Image credit: SpaceX

There was a story last week that SpaceX was asking for a way to "launch Starship at least nine times this year."  That would require a more streamlined response process from the FAA and everyone concerned, but we'd love to see it. March 18th will be four months since IFT-2.  Things would have to be moving much faster than we see for that to happen.