Thread by @SpaceflightNow

Starting now, NASA, Boeing and ULA will provide an update on the Starliner Crew Flight Test, which is currently set for no earlier than June 1.

Listen along on Launchpad Live here:

Follow this thread for written updates. 🧵1/n

2/ Here are the participants on the call today:

3/ Free begins the call by thanking the teams at NASA, Boeing and ULA for their analysis since the May 6 scrub.

"We are learning more about the systems every day."

Free says the teams were "working up to late yesterday, coming to a conclusion," adding that he hears the frustration about the timing of sharing the information about what has been happening over the past few weeks.

4/ Bowersox says he briefly sat in on a meeting yesterday with NASA, Boeing, ULA and Aerojet Rocketdyne where he said it was impressive to see the team working "so thoroughly, so collaboratively through a very, very complicated issue."

5/ Stich says they've been working through "three specific issues" over the last two-and-a-half weeks.

6/ The issues are, per Stich:

1) The swap out of the Centaur oxidizer regulating valve on Atlas 5
2) A helium leak in one of the doghouses on the Starliner service module
3) Implications of the leak for the rest of the propulsion system "relative to the deorbit burn"

7/ Stich says the valve was able to be replaced over the weekend of May 11 and 12, adding that Gary Wentz will provide more information.

8/ Regarding the helium leak, Stich said that the leak (on the port-side doghouse) increased from about 7 PSI to between 50-70 PSI.

He says they weren't able to open up the flange because as it stands, that part of Starliner wasn't safe to open up in the Vertical Integration Facility. So, they did "an analysis-based approach" to understand the leak.

9/ Stich said there are eight total helium manifolds on the service module and there was only a leak found in one of them. There are 28 total RCS thrusters across the SM and only one had the leak.

Regarding the redundancy capabilities of Starliner, Stich says their diagnosis is that the system can "handle up to four more leaks," adding that they could also move forward if the current leak rate went up to "100 times" what they're currently seeing.

10/ Stich said they also looked at finding redundancy for the deorbit burn. He says with the right circumstances, they could lose 8 reaction control system (RCS) thrusters.

The solution was to be able to break up the burn into two burns about 10 minutes each about 80 minutes apart.

11/ There will be a delta flight readiness review on May 29, which if it is approved, they will roll the Atlas V rocket out to the pad on May 30.

Stich says they've been in continuous contact with the crew about the process and analysis.

12/ Weigel notes that there's a Progress spacecraft undocking from the ISS on May 28, which will be followed by Progress 88 launching on May 30 around 5:45 am EDT (0945 UTC).

13/ Nappi says the crew has tested some of the backup scenarios that Stich described (likely in the high-fidelity simulator at the Johnson Space Center).

14/ Wentz noted that they structurally relieved the stress on Centaur, what they call "stretching," in order to access the valve and make the replacement.

He says their work was completed by May 13.

15/ Stich elaborates on the loss of redundancy potential concerning the deorbit burn, he says they would have to be next to each other and have a total loss of the manifold.

16/ Nappi says Starliner won't be the timeline issue for flight, if things push beyond those dates in early June, but rather on the Atlas V rocket.

Wentz says certain elements expire "throughout June and into July." They would also need to work with their launch customers on the manifest, if there's a longer delay.

17/ Stich says that the leak is currently stable and says they would keep the system open all the way from launch through docking and then close it. They can then assess the leak rate at that point and then open it back up when they're ready to undock.

18/ Backup dates beyond June 1 would happen at the following dates and times:

• June 2 12:03 pm EDT
• June 5 10:52 am EDT
• June 6 10:29 am EDT

19/ Stich says they didn't see the leak until after the scrub. So, had the scrub not happened, they may have seen the discovered the issue in flight and addressed it while on orbit.

20/ Steve says leak caused them to look with a bit more detail at the manifolds.

Regarding if they should've seen this earlier, "I think maybe in a perfect timeframe we might have identified this earlier."

21/ Asked if this should've been caught earlier, Mark says he's not concerned with their process leading up to this.

Stich reiterates that this is a test flight, saying that the leak doesn't necessarily implicate the design as being inherently flawed. "Helium is a tiny molecule, it tends to leak."

22/ Nappi reiterates that it wasn't until the post-scrub activities that the leak was discovered.

The crew will be flying back to Florida on May 28, per Stich.

23/ Nappi says, regarding the metal-to-metal on the flange, the leak rate "would not exceed our capability to manage the leak."

24/ Stich says the seal is about the same size as the button on a shirt and is made of rubber, similar to what you'd find on a kitchen sink. He says it's about the thickness of about 10 sheets of paper stacked together.

25/ Nappi said if they were to change the seal out, they characterize it as "hazardous," adding that the work would need to return to the C3PF to do that.

26/ Stich says they don't plan on making changes to the ascent timeline and the manual checkouts that will happen with the crew, as related to the leak.

The nominal plan for return is to execute the same deorbit burn seen on the Orbital Flight Test and OFT-2 as well.

27/ Stich says they have two main areas of confidence for flying with the leak:

1) Characterizing the leak through various pressure cycles (says the leak is "relatively stable")
2) They are able to manage a leak that is 100 times worse than the one they have on their hands right now

28/ Nappi confirms that the system is provided by Aerojet Rocketdyne and they helped provide a better understanding of the thruster and their approach to addressing it.

He says they've looked at four or five different solutions and will apply one of those moving forward on the operational flights of Starliner.