NASA has released a sweeping investigation report into the propulsion system failures that plagued Boeing’s CST-100 Starliner during its Crewed Flight Test (CFT) last year. The report finds a cascade of hardware failures, qualification gaps, organizational breakdowns, and a culture that prioritized schedule and provider success over engineering rigor in the program.
NASA managers say they are close to a decision on when and how they plan to bring Boeing Starliner Crewed Flight test astronauts from the International Space Station. The mission was originally slated to run eight days, but the pair have been in orbit for sixty-three days since their June 5th launch from Cape Canaveral Space Force Station aboard an Atlas V.
“I don’t think we’re too far away from making that call,” Ken Bowersox, NASA’s Associate Administrator for Space Operations Mission Directorate said this afternoon. He added, “We know that at some point we need to bring Butch and Suni home [but] while they’re up there, we have extra crew, we have extra hands, they can do a lot more work, but they’re also using up more consumables, more supplies.”
“As we’ve said before, our prime option is to return Butch and Suni on Starliner, however, we have done the requisite planning to make sure we have other options open.”
Steve Stich, NASA’s Manager for the Commercial Crew Program, August 7, 2024
Bowersox added that Williams and Wilmore may not return on the Starliner spacecraft. “In the case that we have with the Starliner crew,” he said, “the option to either bring the crew home on the Starliner or to bring the crew home on another vehicle. We could take either path, and reasonable people could pick either path depending on where their view is on our position in the uncertainty bound that we have for the date.”
“We have been working with SpaceX to ensure that they are ready to respond on Crew 9 for a contingency of returning Butch and Suni on Crew 9,” Bowersox said. “If we need that we have set up the [Crew] Dragon for Crew 9 to have flexibility to have only two passengers fly up on that flight.”
One thing that NASA did not disclose is which two of the Crew 9 crew would potentially be taken off the mission should the need arise. “We’re not really ready to share the data on which crew members,” said Steve Stich. “I think we’ll do that at the appropriate time.”
The reason for the uncertainty is well-documented: Starliner has thruster problems on its Service Module, and engineers and mission managers within NASA are not unanimous that the spacecraft can be safely flown until such time as the Starliner capsule would separate from its troubled SM and then begin re-entry.
Bowersox said, “We’ve got on the thruster system, on the propulsion system. Moving forward, what we’re trying to do is reduce that uncertainty, see if we can drive some more consensus, amongst our team at the same time getting more serious about evaluating our other options. It’s been really great to watch our team working, our Boeing team, our NASA team, the way people are speaking up; the way we’re hearing different voices, different thoughts on how critical different factors are in the decision.”
“I think it’s been very healthy,” Bowersox said, speaking about the debate behind the scenes. “I have to admit that sometimes when we get this agreement, it’s not fun. It can be painful having those discussions, but it’s what makes us a good organization and it’s what will get us to a good decision as we approach that point here in the future.”
“And I don’t think we’re too far away from making that call.”
Steve Stich, NASA’s Manager for the Commercial Crew Program, gave an in-depth rundown of the technical aspects of Starliner’s issues:
“I’ll talk a little bit more about the manifest changes we’ve made and what we’ve done to give ourselves some flexibility in the near term relative to all the options that we’re looking at. So, if we start with Starliner last time we talked a lot about testing results at White Sands, we had completed the thruster testing, which was essentially two uphill [ascent to ISS after launch] profiles trying to get to the temps that we saw on this particular thruster.”
“And then we really have done five downhill [undocking and free flight to reentry] profiles with that particular thruster. We were able to replicate degradation in the thruster during. That testing, and we saw that continually on the downhill side with the thruster thrust levels degrading over time, which seems to mimic what we’re seeing in flight to some extent during those downhill profiles, as we talked about during that testing, we gained insight into what we think one of the contributing factors are for that thrust degradation.”
Stich continued: “And that would be this Teflon seal on the oxidizer line poppet. Now, this poppet’s really small. It’s about, if you hold up your little pinky finger, it’s about the size of that. A little bit smaller even than your pinky finger. So it’s a small poppet. But what we saw during that testing is the swelling of that Teflon seal.”
“It kind of extruded a little bit. And what happens with that seal is it blocks the flow into the thruster itself, down into the combustion chamber. So we know that’s happening. We know we can get vaporization when it gets hot in that line, bringing propellant into the thruster.”
“And also when that poppet is blocked by the Teflon seal, we see some cavitation, in other words, unsteady flow across that poppet. We have some animation that we hope to be able to release soon to you. So you can see what this is like. Boeing has been doing a lot of work on that animation.”
“Hopefully, we can have them share that soon so you can get a better idea of that mechanism as well. We also have this same theory that has some vaporization of the propellant, right, and it drops the thrust. So there’s really two key things that we think is happening. One, when the thruster gets really hot, the propellant can vaporize.”
“That’s where we saw the really low thrust readings on docking day. And then as the poppet swells, we can get some blockage there. Based on what we learned at White Sands, what we’re trying to do now is sort of understand what all that data means to us from the white sands testing and then what it means to the thrusters on orbit.”
“We did do a hot fire while we’re docked to the International Space Station on Saturday, July 11. we wanted to understand the performance of all the thrusters across the vehicle. So we hot fired all 27 thrusters. We did not hot fire one thruster in the bottom doghouse.”
“We call it the B1-A3 thruster. That one had really low thrust before, during the dock when we were docking back on July 6. And so we did not. Or June 6, and we did not hot fire that thruster. The interesting thing when we hot fired the thrusters is all the thrusters now across the whole vehicle are essentially at nominal thrust level.”
“So, for example, the one that we saw the most degradation in the two. A two was at about 80% before the hot fire, and now it’s about 98%. So somehow, if the poppet is the theory of what’s causing the thrust degradation, the blockage in that ox flow, somehow that piece of Teflon must have contracted and is now not blocking the flow like it was.”
“And so we have a nominal flow, essentially, into that. Thruster and nominal thrust. What we’re really trying to do now, that gives us a lot of confidence in the thrusters, but we can’t totally prove with certainty what we’re seeing on orbit is exactly what’s been replicated on the ground.”
“We’re trying to understand a little bit more about the conditions that cause the thruster fail-offs. It’s not always at the same temperature. It’s not always at the same number of pulses. And so we’re trying to understand that we are doing modeling on the ground to try to understand how this Teflon could extrude what the forces are on that Teflon.”
“And then trying to understand how it could contract over time. People really want to understand the physics of what’s going on relative to the physics of the Teflon, what’s causing it to heat up, what’s causing it to contract. And that’s really what the team is off trying to understand. And then look ahead toward the downhill phase and the heating on the downhill phase and seeing if we can model that on the downhill phase and ensure we have good thrusters.”
“Again, we have really good knowledge of what the downhill is. But how does that really help us out?”
“In combination with that, we have tried to buy ourselves a little bit of time to work various options for return. And so recently, this week at the Program Control Board, just yesterday, we approved moving the Crew 9 mission to no earlier than September 24. We took that to the Program Control Board, and it was approved.”
— Steve Stich, August 7, 2024
“We have been working with SpaceX to ensure that they are ready to respond on Crew 9 for a contingency of returning Butch and Suni on Crew 9 if we need that. We have set up the dragon for Crew 9 to have flexibility to have only two passengers fly up on that flight,” Stich said.
“And then we could return four crew members in the February 2025 timeframe. And Butch and Suni would remain on station and become part of that increment and return home with them on Crew 9. Now, we haven’t approved this plan. In other words, we’ve done all the work to make sure this plan is there.”
“We have the suits identified to fly up on Crew 9. We have the seats set up so that we can fly multiple complement of people. But we have not turned that on formally, as that’s the path that we’re going to go down. But we wanted to make sure we had all that flexibility in place.”
“We’ll fly up the supplies needed on that Crew 9 flight, including any suits needed for butch and Suni. You know, we’ve done previous work with that for other contingencies. And we’ll have the foam inserts to work on all the seats for the various crew members.”
“So we’ve done a lot of contingency work and a lot of contingency planning for a lot of scenarios, but we think now we would have the whole waterfront covered. As I said, we haven’t really implemented planning for the mission for these things, but we have all the items in place to keep all the options on the table.”
That said, it appears that NASA is keeping its options open by thoroughly investigating and completing at least preliminary plans for the option of returning the Boeing Starliner CFT astronauts on a SpaceX Crew Dragon.
At the end of the press conference several things were clear: first, that NASA is undecided on whether to return Wilmore and Williams to Earth using Starliner, second, that there are disagreements within NASA about doing that, and third, that returning on a SpaceX Crew Dragon is a very real possibility with planning already started for that option as a contingency.
I was not able to be present at Cape Canaveral for the actual launch of Starliner due to prior commitments and the two previous scrubs of the flight moving the schedule into the middle of another long-planned trip. Disappointing, but things happen. I was, however, able to capture a lot of the prelaunch activities:
After a day of speculation and probably leaks of the information on background, NASA, Boeing and United Launch Alliance have announced that they are pushing the schedule back another four days for the Crewed Flight Test of Starliner. The launching will be “no earlier than 3:09 p.m. EDT Saturday, May 25, for the flight test carrying NASA astronauts Butch Wilmore and Suni Williams to the International Space Station,” according to a release from NASA.
As to the reason for the new delay, NASA stated:
“The additional time allows teams to further assess a small helium leak in the Boeing Starliner spacecraft’s service module traced to a flange on a single reaction control system thruster. Pressure testing performed on May 15 on the spacecraft’s helium system showed the leak in the flange is stable and would not pose a risk at that level during the flight. The testing also indicated the rest of the thruster system is sealed effectively across the entire service module. Boeing teams are working to develop operational procedures to ensure the system retains sufficient performance capability and appropriate redundancy during the flight. As that work proceeds, NASA’s Commercial Crew Program and the International Space Station Program will take the next few days to review the data and procedures to make a final determination before proceeding to flight countdown.“
NASA, Boeing Now Working Toward May 25 Launch of Crew Flight Test
Reading between the lines, it seems that the leak has not been repaired but is instead “stable.” NASA and Boeing now have to “assess” whether this is an acceptable condition for flight. That decision will be made in the next few days and then everyone will have a better idea of when Starliner can launch with crew aboard for the first time.
The prime and backup crews for the upcoming Boeing Starliner Crewed Flight Test arrived at Kennedy Space Center this afternoon. They landed on the storied Launch and Landing Facility (LLF) formerly known as the Shuttle Landing Facility (SLF) — the same runway that Space Shuttle orbiters returned to at the completion of their missions.
After offering some remarks and answering questions from the press, the crew departed to begin final preparations for their upcoming launch, planned for May 6, 2024, at 10:34 PM EDT. After a successful liftoff and some time in orbit to catch up with the International Space Station, the pair will dock at the orbiting laboratory and stay for about a week.
Wilmore began his remarks by saying, “Suni and I were talking. We love Florida! We love Kennedy Space Center because this is where you launch humans into space.” True, and Wilmore thanked everyone working on the upcoming Starliner launch. “You just want to mention everybody’s name,” he said. Wilmore then pointed out the NASA, Boeing and United Launch Alliance managers present at the arrival and thanked them and the backup crew members and other astronauts working this launch alongside the prime crew.
United Launch Alliance and Boeing transported the CST-100 Starliner capsule from Boeing’s preparation facility aside the VAB early this morning and transported it to SLC-41 for mating to its booster, an Atlas V N22. Launch of the Crewed Flight Test is scheduled for NET May 6, 2024, with an eight day mission planned for crew and spacecraft.
On hand to greet Boeing employees and members of the press were CFT Pilot Sunita “Suni” Williams and CFT Commander Barry “Butch” Wilmore. The two thanked everyone for coming out to greet them early in the morning, and they expressed their confidence in a great mission to come. “We’re super proud of this team,” Williams said. “They made it happen, and it’s time to turn [Starliner] over from production to operations.” With that, the pair expressed their readiness to go fly aboard Starliner.
First, and foremost, Boeing and NASA mission managers would like to see a relatively event-free maiden crewed flight of Starliner, with no unexpected major incidents. Boeing’s Starliner has flown twice, once in 2019 and once in 2022, and neither time with crew aboard.
The first flight, Orbital Flight Test 1 (OFT-1), in 2019, failed to reach the International Space Station (ISS) after the on-board clock malfunctioned. The second flight, Orbital Flight Test 2 (OFT-2), in 2022 met all of its major objectives and docked with the ISS, where it remained for four days before returning to Earth.
Since the second flight, other problems, including a potentially flammable tape used to wrap the wiring harnesses of Starliner were replaced, issues with parachute lines and its harness were improved and tested, and software improvements were made. Those remediations held up this Crewed Flight Test until earlier this year, and after that, scheduling issues on the International Space Station ports has kept Starliner on the ground.
Now that the ISS docking ports are clear and technical issues have been resolved, Boeing, United Launch Alliance and NASA have begun their launch campaign, which begins in earnest with a planned liftoff no earlier than May 6th.
Last month, Mark Nappi, Boeing’s Vice President and Program Manager of the Starliner Program outlined what promises to be a busy schedule for Williams and Willmore during the flight. “The CFT flight is really the introduction of crew into our vehicle system. So a lot of our flight test objectives are about how that interface is going to work.”
Nappi said regarding flight test objectives, “We’ve got just under 90 of them. And it’s all, does the vehicle perform with the human in the loop, as expected?”
“We flew OFT-2,” Nappi added, “And that was the uncrewed mission for the Starliner vehicle. It was very successful. Now we introduce the human. And so what are we going to do to establish that interface?”
“From prelaunch through ascent, we’re going to be looking at how the astronauts fit into the seats, how they interface with the equipment in the vehicle. when we go through approach and rendezvous.” After that, Nappi said, “We’ll confirm the thruster performance and manual scenarios are working as expected. We’ll check the communications. We’ll check the manual and auto navigation systems and the operation of the life support system with crew now in the vehicle.”
“CFT is a test flight, so we expect that there may be some lessons learned,” Nappi concluded.
Today was an active day for launch scheduling: United Launch Alliance has announced that they will make their next attempt to launch Delta IV Heavy and NROL-70 on Tuesday April 9th, and later, NASA announced that the Crewed Flight Test of Boeing’s Starliner is now Monday, May 6th.
Delta IV was scrubbed at T-min 3:58 by a faulty gaseous nitrogen pump on its first attempt March 28, and at the time, ULA engineers and CEO Tory Bruno were optimistic that a second attempt could happen the next day. Unfortunately, the pump failed again, and ULA stated that they would announce a new launch date only when they were certain that they and NASA (who provides the N2 service to the pad) were past the problem.
Today ULA released their new target date:
DELTA IV HEAVY TO LAUNCH NROL-70
“A United Launch Alliance (ULA) Delta IV Heavy rocket is launching the NROL-70 mission for the National Reconnaissance Office (NRO) from Space Launch Complex-37 at Cape Canaveral Space Force Station, Florida. This is the 16th and final launch of a Delta IV Heavy rocket.
Launch Date and Time: April 9 at 12:53 p.m. EDT, pending range approval
GO Delta IV Heavy! GO NROL-70!“
United Launch Alliance, April 2, 2024
The launch will be from SLC-37 at Cape Canaveral Space Force Station.
Later on in the day, rumors of a shift in the Starliner launch date from May 1st came to pass when NASA made this announcement:
NASA, Boeing Update Launch Date for Starliner’s First Astronaut Flight
“Following a review of the International Space Station operations, NASA’s Boeing Crew Flight Test now is targeting no earlier than Monday, May 6, for Starliner’s first launch with astronauts to the orbital complex. The date adjustment optimizes space station schedule of activities planned toward the end of April, including a cargo spacecraft undocking and a crew spacecraft port relocation required for Starliner docking. NASA and Boeing also are performing prelaunch closeout work and completing final certification for flight.”
NASA, Boeing Update Launch Date for Starliner’s First Astronaut Flight
It should be noted that Starliner’s launch date was not moved due to any technical issue, but instead because of ISS logistics.
NASA Astronauts Suni Williams and Butch Wilmore will be aboard Starliner when it heads to the International Space Station for a planned one week stay on the orbiting outpost.
During the NASA Administrator Briefing from the Kennedy Space Center mainly centered around Crew-8 readiness today, Steve Stich, the Manager of the agency’s Commercial Crew Program gave some insight about the status of the planned first crewed flight of Boeing’s CST-100 Starliner. That launch is currently planned for late April of this year.
On the Starliner capsule’s readiness, Stich said “Over at Boeing the Starliner spacecraft is pretty much closed out. We’ve loaded the fluid for the cooling system. The next big event, really, is to load propellant on the crew module and propellant in the service module. And that’ll happen in mid-March.”
“We’re going to work hand in hand with Joel [Montalbano, NASA’s Manager of the International Space Station Program] on the right decision points to go fuel Starliner. As Joel said, it’s a busy time, so we may adjust the date. Right now, we’re targeting the Crew Flight test in late April.”
Stich also mentioned that the launch date for Starliner may be affected by the availability of a docking port, so the late April date appears that it may still be somewhat fluid. The good news for Boeing is that the spacecraft appears to be in good condition to fly, pending additional flight readiness reviews.
On a post on the X platform yesterday, NASA Commercial Crew said “A United Launch Alliance Atlas V rocket was moved into the company’s Vertical Integration Facility to start stacking operations ahead of the first crewed Starliner launch to [the International] Space Station.”
Stich said that there are effectively two crews training for Starliner flights: “We really have two crews, primarily in training,” he said. “Barry Wilmore and Sunita Williams, for CFT. Mike Finke is the backup astronaut for that flight.”
Stich did not identify an additional astronaut that would be training for Starliner One, the first operational mission of the CST-100 Starliner system. He did, however, outline post-CFT plans for the Starliner system. “Our plan is to really watch the progress of how Starliner One is progressing with the hardware build and the certification products,” he said.
“Just like we did for [SpaceX Crew Dragon] Demo-2, to get to our [Starliner] Crew One flight,” Stich added, “We have a certification process that we go through after that test flight to get to the first Starliner mission. We’ll do that toward the end of this year.”
Assuming all goes well for the Starliner CFT mission, Stich said that, “The Starliner One mission is scheduled for February of 2025.”
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