SpaceX Replacing 2 Rocket Engines for NASA Crew-1 Astronaut Launch

SpaceX vendor left residue, blocked Falcon 9 vent holes

Since then, the investigation has discovered the issue: two of the nine Merlin engines installed in the first stage of the Falcon 9's first stage have retained a residue of a "masking lacquer" used to protect sensitive parts during anti-corrosion anodizing treatment, said Hans Koenigsmann, SpaceX vice president of build and flight reliability, during a Wednesday news conference.

SpaceX's vendor who performed the above treatment hadn't removed all of the lacquer after application — leaving some of it in a position to block the 0.06-inch-(1.6-millimeter)-wide vent holes for the valves in two of the Merlins expected to power the two-stage Falcon 9's launch on Oct. 2, added Koenigsmann, reports Space.com.

SpaceX investigation carried out with NASA and Space Force

After reviewing much of the Merlin data, SpaceX found traces of a similar issue with two of the engines in the first stage of the Crew-1 Falcon 9 — in addition to one Merlin in the first stage of the booster slated to carry the Sentinel-6 Michael Freilich Earth-observing satellite for NASA and several of its partners on Nov. 10, reports The Verge.

As of writing, SpaceX is swapping the affected Merlins out for ones without the masking-lacquer residue, explained Koenigsmann.

SpaceX carried out the investigation and troubleshooting process with NASA and the Space Force, which "led to a really good review and a really good anomaly resolution that, in my opinion, makes a better vehicle and a better engine going forward," added Koenigsmann.

SpaceX, NASA's Crew-1 Falcon 9 mission possibly saved

The safety systems aboard SpaceX's Falcon 9 worked perfectly on Oct. 2, detecting the anomaly and aborting the launch in time, said Koenigsmann. But a liftoff may have gone just fine, he added, saying: the Falcon 9 could have undergone a "hard start" created when various fluids — like liquid oxygen, kerosene, and igniter fluids — are introduced in the wrong order in the engines.

"It's not necessarily bad," said Koenigsmann about the possibility of a hard start. "In most cases, it rattles the engine, and it may cause a bit of damage to the engine. In extreme cases, it may cause more damage to the engine."

Whether SpaceX and NASA narrowly avoided a minor disaster on Oct. 2, we'll never know. But one thing's for certain: the upcoming Crew-1 Falcon 9 mission is more secure thanks to the safety systems aborting the Oct. 2 mission, two short seconds before liftoff.