A "subtle" engine problem that triggered theof a SpaceX Falcon 9 rocket earlier this month has been resolved, engineers believe, and if ongoing tests go well, NASA plans to press ahead with the atop another Falcon 9 on November 14, officials said Wednesday.
In the meantime, SpaceX "Crew-1" commander Michael Hopkins, pilot Victor Glover, Shannon Walker and Japanese astronaut Soichi Noguchi went into initial quarantine last weekend, taking additional steps beyond those already in place due to the coronavirus to ensure all four are virus-free for launch.
Liftoff from historic pad 39A at the Kennedy Space Center is targeted for 7:49 p.m. EST on Saturday, November 14. If all goes well, the Crew Dragon will execute an automated rendezvous, docking at the space station's forward port eight-and-a-half hours later, around 4:04 a.m. the next day.
If bad weather or other issues delay an on-time launch, the crew has a backup launch opportunity at 7:27 p.m. on Sunday, November 15, setting up a docking the following day. If not off the ground by then, the crew likely would have to wait until after a Russian spacewalk on November 18.
"The crew's doing well," said Steve Stich, manager of NASA's Commercial Crew Program. "As we started to work through the (engine) anomaly and started to see a path to get to flight on the 14th, we did put the crew in a soft quarantine over this past weekend.
"They've been in a lot of the telecons and listening to what's going on with the vehicles. We have a little bit more work to do on this engine anomaly, but I think we see a pretty good path to (launch). We'll fly when we're ready."
NASA managers originally hoped to launch the SpaceX Crew-1 mission earlier this month. But the flight was delayed, first to allow more time between Rubins' October 14 launch and the return to Earth of another three-man Soyuz crew on October 21, and then because of a last-second Falcon 9 launch abort Oct. 3.
The Falcon 9, carrying a U.S. Space Force Global Positioning System navigation satellite, was not damaged, but the flight was put on hold while engineers worked to pin down what went wrong and what might be needed to prevent additional problems.
During a teleconference Wednesday, Hans Koenigsmann, SpaceX vice president for Build and Flight Reliability, said the rocket's flight computer commanded the abort after detecting unusual pressure readings in the turbopump machinery used by two of the rocket's nine first stage engines.
The suspect engines were removed and shipped to SpaceX's Texas flight test facility where engineers were able to replicate the pressure readings.
Koenigsmann said a detailed inspection revealed a tiny amount of nail polish-like red lacquer, used to clean components after anodizing treatments, that had not been thoroughly cleaned out and had clogged a 1/16th-inch-wide vent line.
As a result, the "ignitor fluid" used to spin up the turbopumps reached the machinery too soon, throwing off the engine start sequence. Had the flight computer not aborted the launch, Koenigsmann said, the engines in question could have been damaged during what he called a "hard start."
"It's not necessarily bad, but in most cases, you know, it rattles the engine," he said, "and it may cause a little bit of damage on the engine. In extreme cases, it may cause more damage. So in general, you do not want that, you want a good startup."
After finding the blocked vent lines in the two engines responsible for the abort, SpaceX reviewed data from engines across its fleet of Falcon 9 rockets and found three more with similar problems: one slated for use November 10 to launch an Earth science satellite from California and two in the Crew-1 Falcon 9.
In all five cases, the blocked vent lines were found in new Merlin engines that have not yet flown to space.
Koenigsmann said SpaceX is working with its vendors to make sure the hardware is more thoroughly cleaned and inspected in the future, before new engines are built. The company also is re-assessing other components that might be susceptible to similar issues.
In any case, all five engines are being replaced with thoroughly inspected Merlins known to be free of any such blockages.
SpaceX plans to make another attempt to launch the Global Positioning System satellite next Thursday, sources say, followed by launch of the Sentinel 6-Michael Freilich Earth observation satellite on Nov. 10.
Stich said the Crew-1 launch date will depend, in part, on results from the GPS launch next week to make sure that other, unspecified changes work as intended during the piloted flight.