I'm sorry, but this is a major red flag! Critical control systems should not be leaking. Ever! Crazy that they've put people on this with such faults.
Boeing have really lost the plot.

Finally docked at the ISS at the second attempt after more problems. Big pucker factor coming home if anything similar happens during re-entry.

The first docking approach was aborted when they were ordered to retreat to a holding pattern 200m away known as the “keep out sphere” after five of the manoeuvring thrusters failed to fire.

https://www.space.com/boeing-starlin...ocking-attempt

…..”Starliner missed its first docking chance, at 12:15 p.m. EDT (1615 GMT), after five of its 28 reaction-control thrusters malfunctioned. But the mission team got four of those impacted thrusters back online, and Starliner was cleared to approach the ISS in the next window.”….

Move along there folks! Nothing to see here….

https://arstechnica.com/space/2024/0...finds-its-way/

….However, the Boeing official speaking to reporters on Thursday, Nappi, sought to downplay the severity of the issues confronted by Starliner and its flight controllers. There are two primary problems, he said, the helium leak and the intermittent thruster problems.

"Those are pretty small, really, issues to deal with," he said. "We’ll figure them out for the next mission. I don’t see these as significant at all."

https://spacenews.com/fifth-helium-l...-on-starliner/

Fifth helium leak detected on Starliner

WASHINGTON — NASA confirmed that Boeing’s CST-100 Starliner spacecraft has suffered a fifth, although minor, helium leak in its propulsion system as engineers work to prepare the vehicle for its return to Earth next week.

In a June 10 statement, NASA mentioned that spacecraft teams were examining “what impacts, if any, five small leaks in the service module helium manifolds would have on the remainder of the mission.”

That was the first reference to there being five leaks in the spacecraft; NASA had mentioned there were four in a briefing hours after the spacecraft’s June 6 docking with the International Space Station.

In a June 11 statement to SpaceNews, NASA spokesperson Josh Finch said the fifth leak was detected around the time of that post-docking briefing. “The leak is considerably smaller than the others and has been recorded at 1.7 psi [pounds per square inch] per minute,” he said.…..

It's a test flight, but still... :ooh:

https://spaceflightnow.com/2024/06/2...turn-to-earth/

NASA again delays Starliner undocking, return to Earth

NASA and Boeing managers have again decided to extend the Starliner crew capsule’s stay at the International Space Station, passing up a June 26 re-entry to allow more time for analysis and testing to make sure helium leaks and thruster failures are fully understood, officials said late Friday.

NASA plans to hold a formal re-entry readiness review before setting a new landing target date. Given the on-going analysis, the Starliner’s undocking and return to Earth likely will slip past two already planned space station spacewalks on Monday and July 2.

In the meantime, Starliner commander Barry “Butch” Wilmore and co-pilot Sunita Williams are still cleared to undock and fly home at any time if a station malfunction or other issue crops up that requires a quick departure. As such, officials say they are not stranded in space.

“We are taking our time and following our standard mission management team process,” Steve Stich, manager of NASA’s Commercial Crew Program, said in a statement. “We are letting the data drive our decision making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking.”

In addition, he said, given the extended duration of the Starliner mission “it is appropriate for us to complete an agency-level review, similar to what was done ahead of the NASA’s SpaceX Demo-2 return after two months on orbit, to document the agency’s formal acceptance on proceeding as planned.”

He was referring to the first flight of astronauts aboard SpaceX’s Crew Dragon ferry ship in 2020. But the Demo-2 mission did not experience problems like the ones noted so far in the Starliner’s first piloted test flight.

The issue for Starliner troubleshooters is that the helium leakage and the thrusters in question are located in the Starliner’s drum-shaped service module, which is attached to the base of the crew capsule. The service module is jettisoned prior to re-entry and burns up in the atmosphere.

Given that engineers will not be able to examine the actual hardware after the fact, NASA and Boeing managers want to give them as much time as possible to review telemetry, to continue testing and to polish contingency scenarios in case additional problems show up after undocking.

They also want to learn as much as possible about what might be needed to prevent similar problems in downstream flights. NASA managers were hoping to certify the Starliner for operational crew rotation flights to the ISS starting early next year, but it’s not yet clear if that’s remains a realistic goal......

The continued postponement of Starliner's re-entry date concerns me. If helium leaks represented a threat to safe flight, the craft would have been brought home soonest to limit pressure loss. Malfunctioning and non-functioning thrusters are a matter of grave importance. Correct flight attitudes during re-entry are critical; axis excursions might lead to loss of crew. Perhaps there is another glitch of which we are unaware. Do Boeing and NASA know something we don't? Fingers crossed for Butch and Suni.

- Ed

Could they "just" take another vehicle back to earth and let Starliner return unmanned? It seems to need human astronauts for control?

There needs to be sufficient emergency escape vehicles available for all crew. Can they fit two more in a Dragon?

The (possibly) faulty thrusters are located in the Service Module, so whilst they may have a role in ensuring correct attitude for retro fire they would be long gone by the time the crew get to re-entry itself.

Which is part of the reason why they are delaying the return - the Service Module is destroyed during re-entry, so they can't examine the faulty thrusters. So they are doing various testing while docked to evaluate what's going wrong in an effort to isolate the root cause.

Points well made, wiggy and tdracer, but I continue to worry. If the Starliner has any commonality with its Mercury, Gemini, and Apollo predecessors, thrusters on the capsule itself are utilized throughout the re-entry phase up until drogue deployment. Do we know if the vehicle's thrusters are similar to those on the Service Module? Does it really take three weeks to run diagnostics on the Module's systems? I sense something is afoot of which we are unaware and sincerely hope that I am wrong!

- Ed

The starliner capsule reentry control thrusters are supposed to be traditional hydrazine units - Aerojet Rocketdyne MR-104J

I think Dragon was originally designed to carry seven astronauts if needed, but they generally fly with four and may not have additional seats available.

Designed for 7 so the environmental system can cope. Don’t have the SpaceX suits, but they’re a safety measure not a necessity. Plenty of space where the other seats were so padding could be added in the floor. So it is doable in an emergency.

But so is use of the Starliner itself. The delay is risk mitigation, not that there is a known problem which would endanger re-entry.

If there are doubts the safest option would be for them to remain aboard till the next Dragon crew rotation flight in August. Planned for 4 crew rotation but they could launch with just 2 plus extra suits and recover them with two of the planned returnees, extending the tours of the other 2.

That would reduce the total crew to the previous planned complement.

Starliner could be released before the arrival to do another automated test re-entry, freeing the docking bay.

If the Starliner crew have to be recovered on a Dragon, and the Starliner re -enter unmanned, I fear that will be the end of the whole Starliner program...I think that I read that Boeing are never going to recoup the money that they have spent on the program, and so cut their losses...
Lets see if the July date is kept..

https://www.bbc.com/news/articles/c6pp29gdwe6o

There’s a reason you should do a LOT of testing before launch. :ouch:​​​​​​​

https://www.avweb.com/aviation-news/...ir-confidence/

SpaceX was awarded $267K on July 15 for "Special Study for Emergency Response."

A similar contract was awarded when NASA considered Frank Rubio on Dragon.

During the July 10th press conference, Steve Stich, program manager for NASA’s Commercial Crew Program, mentioned NASA had looked at Dragon contingency per Butch and Suni waiting for Starliner to be cleared for return, so this may be related.

And we have a NASA response for context:

"The study is not related to Starliner. NASA continuously explores a wide range of contingency options with our partners to ensure crew safety aboard the International Space Station.

Over the past couple of years, the agency has worked with its commercial partner SpaceX to provide additional return capability on the Dragon spacecraft in the event of a contingency."

“additional return capability on the Dragon spacecraft in the event of a contingency”. Like for stranded astronauts?

But sure, this emergency 1 month long contract has nothing to do with the currently stranded Starliner 🙄

​​​​​​​Is this US Govt BS month or something and I missed the announcement?

Starliner update:

Teams completed ground hot fire testing at White Sands and are working to evaluate the test data and inspect the test engine. The ongoing ground analysis is expected to continue throughout the week.

Steve Stich, manager, NASA’s Commercial Crew Program: "We collected an incredible amount of data on the thruster that could help us better understand what is going on in flight. Next, our team has moved into engine tear downs and inspections which will provide additional insight as we analyze the results and evaluate next steps."

​​​​​​​https://blogs.nasa.gov/commercialcre...inue-analysis/

I believe I would think twice before an atmospheric plummet aboard Starliner.

- Ed

After weeks of troubleshooting and recent tests meant to replicate the issues plaguing Boeing’s Starliner spacecraft, NASA and Boeing officials still aren’t ready to name a return date for the two astronauts piloting the vehicle on its inaugural crewed test flight.

But engineers do finally have some possible answers about what ultimately caused some of the Starliner’s problems during the first leg of its trip, which included helium leaks and thrusters that abruptly quit working en route to the International Space Station.

The revelations come after Boeing and NASA spent the past couple of weeks working to understand the problem on the ground and prompted plans for some additional testing this weekend, which should serve as “icing on the cake” for understanding the issues, said Mark Nappi, Boeing’s Commercial Crew Program manager.

At a site in New Mexico, engineers fired test engines more than 1,000 times, replicating how the thrusters on the space-bound Starliner would have ignited. They then fired the thruster to try out several ways the engines might fire on the way home from space, according to Boeing.

The goal of this testing was to gain a better understanding of why the spacecraft’s thrusters unexpectedly shut down, and what — if any — dangers are associated with turning those thrusters back on.

Officials said they were able to recreate how the thrusters in space deteriorated during flight with the ground tests. And the testing may have helped give engineers a better understanding of the issue’s “root cause”: Heat building up inside the thrusters may be causing Teflon seals to bulge, restricting the flow of propellant.

That testing has “given us additional confidence to undock in return,” Nappi said.
https://s.yimg.com/ny/api/res/1.2/f_...23b754a4b7a0f2Boeing’s Starliner spacecraft that launched NASA’s Crew Flight Test astronauts Butch Wilmore and Suni Williams to the International Space Station is pictured docked to the Harmony module’s forward port. - NASAThe findings also prompted Boeing and NASA to abandon plans to allow the astronauts to manually fly the Starliner spacecraft on the way home, as they did briefly during the trip to the ISS. “Some of the manual maneuvering put some extra stress on the thrusters,” said Steve Stich, NASA’s Commercial crew program manager.

Still, officials did not definitively say Thursday that the Starliner spacecraft that carried veteran NASA astronauts Butch Wilmore and Suni Williams to the space station would be the same vehicle that brought the astronauts back home.

“There is a lot of good reasons to complete this mission and bring Butch and Suni home on Starliner,” Stich said after noting that NASA does have contingency options if Starliner is not approved to bring the astronauts home.

“We need to get through the process,” he added. “We have another critical Starliner mission management team to review all the thruster data that we just talked about.”

“Of course, I’m very confident we have a good vehicle to bring the crew back with,” Nappi said.

Williams and Wilmore arrived at the International Space Station on June 6 for what was expected to be a roughly week-long mission. As of Thursday, the astronauts have been in space for about 50 days. NASA has previously indicated that the Starliner can stay in space for a maximum of 90 days.

Additional Starliner testing

Separately, engineers may have made headway understanding helium leaks that hampered the first leg of Starliner’s journey. But Boeing and NASA will take a close look at that issue again during additional testing of the vehicle in space that will continue this weekend, Stich said.

That testing will include firing 27 of the Starliner’s thrusters while the vehicle remains docked with the ISS.

Analysis of components on the ground — specifically, a version of the Starliner’s service module that’s been sitting in White Sands, New Mexico for three years — showed that the helium leaks may be a result of seals that have become degraded because of exposure to propellant vapor, according to Nappi.

“The natural fix to that is to just change that seal out to a material that’s not so susceptible” to being worn down by exposure to the propellant, Nappi said, referring to possible changes Boeing can make for future Starliner missions.

Still ahead, however, is work to determine whether the leaks on board the Starliner that’s already in space have grown worse as the vehicle has remained docked at the ISS. Because the service module — the portion of the spacecraft plagued by the helium leaks — on the ground was exposed to propellant for so long, Nappi said it could offer a worst case understanding of how badly the seals can be degraded.

The ongoing effort to understand the helium leak issue is among the chief reasons why NASA and Boeing still aren’t able to set a return date for Williams and Wilmore — or give a definitive answer on whether the Starliner is ready to fly them home.

“The key attributes of the flight rationale really are that we understand the helium leaks — we understand the stability of the leaks and how we can manage those, should they get bigger,” Stich said, referring to the possibility that helium leaks affecting the Starliner service module may worsen.

NASA and Boeing plan to carry out a review to plan for Starliner’s undocking, which “could be as early as late next week,” according to Stich.

From CNN

My interpretation of the articles posted by ORAC and cavuman1 is Boeing/NASA finally have an idea of what's going on with the thrusters and helium leaks, but (reading between the lines) don't know if the issues experienced on the way up will cause problems on the way down.

I’m not sure the articles quite capture all the details that were briefed in the on-line presser a few days back. TBH sounds like NASA/Boeing have a pretty good handle on both up and down.

It must be the case that I've watched too many James Bond movies, or maybe I watched an okay quantity and batch but recall too creatively.

Perhaps there is a purpose to the two astronauts staying on ISS which is not being shared with the public.

There has evidently been some anticipatory stockpiling of consummables; no press reports of which I'm aware have noted concern over this factor in crew rotation scheduling and planning.

I can't help wondering if it is such a "no big deal" as they're saying. I wonder what will come out eventually.

https://arstechnica.com/space/2024/0...rliner-issues/

NASA likely to significantly delay the launch of Crew 9 due to Starliner issues

NASA is planning to significantly delay the launch of the Crew 9 mission to the International Space Station due to ongoing concerns about the Starliner spacecraft currently attached to the station.

While the space agency has not said anything publicly, sources say NASA should announce the decision this week. Officials are contemplating moving the Crew-9 mission from its current date of August 18 to September 24, a significant slip.

Nominally, this Crew Dragon mission will carry NASA astronauts Zena Cardman, spacecraft commander; Nick Hague, pilot; and Stephanie Wilson, mission specialist; as well as Roscosmos cosmonaut Alexander Gorbunov, for a six-month journey to the space station. However, NASA has been considering alternatives to the crew lineup—possibly launching with two astronauts instead of four—due to ongoing discussions about the viability of Starliner to safely return astronauts Butch Wilmore and Suni Williams to Earth.

As of late last week, NASA still had not decided whether the Starliner vehicle, which is built and operated by Boeing, should be used to fly its two crew members home.

During its launch and ascent to the space station two months ago, five small thrusters on the Starliner spacecraft failed. After extensive ground testing of the thrusters, as well as some brief in-space firings, NASA had planned to make a decision last week on whether to return Starliner with crew. However, a Flight Readiness Review planned for last Thursday was delayed after internal disagreements at NASA about the safety of Starliner.

At issue is the performance of the small reaction control system thrusters in proximity to the space station. If the right combination of them fail before Starliner has moved sufficiently far from the station, Starliner could become uncontrollable and collide with the space station. The thrusters are also needed later in the flight back to Earth to set up the critical de-orbit burn and entry in Earth's atmosphere.

Software struggles

NASA has quietly been studying the possibility of crew returning in a Dragon for more than a month. As NASA and Boeing engineers have yet to identify a root cause of the thruster failure, the possibility of Wilmore and Williams returning on a Dragon spacecraft has increased in the last 10 days. NASA has consistently said that ‘crew safety’ will be its No. 1 priority in deciding how to proceed.

The Crew 9 delay is relevant to the Starliner dilemma for a couple of reasons. One, it gives NASA more time to determine the flight-worthiness of Starliner. However, there is also another surprising reason for the delay—the need to update Starliner’s flight software. Three separate, well-placed sources have confirmed to Ars that the current flight software on board Starliner cannot perform an automated undocking from the space station and entry into Earth’s atmosphere.

At first blush, this seems absurd. After all, Boeing’s Orbital Flight Test 2 mission in May 2022 was a fully automated test of the Starliner vehicle. During this mission, the spacecraft flew up to the space station without crew on board and then returned to Earth six days later. Although the 2022 flight test was completed by a different Starliner vehicle, it clearly demonstrated the ability of the program's flight software to autonomously dock and return to Earth.

Boeing did not respond to a media query about why this capability was removed for the crew flight test.

Has there not always been a Russian Soyuz craft docked at the ISS, periodically rotated, which can be used at any time to do an emergency evacuation if need be, as well as regular Russian crew changes ? It has capacity for the full complement of ISS personnel at any one time.

Perhaps, but I suspect that is when everyone is leaving or there is another capsule docked.

There are always enough seats on a Soyuz or a Space X Dragon for the current compliment but no spares. If NASA decide to the bring the Starliner crew home on a Dragon capsule the next crew (which is launching shortly) will be reduced to 2 from 4 to free up spare seats.

Consumables isn't an issue, there is always enough to account for at least one, perhaps two, failed re-supply missions.

NASA likely to significantly delay the launch of Crew 9 due to Starliner issues
 

https://arstechnica.com/space/2024/0...rliner-issues/

The primary reason for the delay is rather surprising.
.
As of late last week, NASA still had not decided whether the Starliner vehicle, which is built and operated by Boeing, should be used to fly its two crew members home. During its launch and ascent to the space station two months ago, five small thrusters on the Starliner spacecraft failed. After extensive ground testing of the thrusters, as well as some brief in-space firings, NASA had planned to make a decision last week on whether to return Starliner with crew. However, a Flight Readiness Review planned for last Thursday was delayed after internal disagreements at NASA about the safety of Starliner.
.
The Crew 9 delay is relevant to the Starliner dilemma for a couple of reasons. One, it gives NASA more time to determine the flight-worthiness of Starliner. However, there is also another surprising reason for the delay—the need to update Starliner’s flight software. Three separate, well-placed sources have confirmed to Ars that the current flight software on board Starliner cannot perform an automated undocking from the space station and entry into Earth’s atmosphere.
.
At first blush, this seems absurd. After all, Boeing’s Orbital Flight Test 2 mission in May 2022 was a fully automated test of the Starliner vehicle. During this mission, the spacecraft flew up to the space station without crew on board and then returned to Earth six days later. Although the 2022 flight test was completed by a different Starliner vehicle, it clearly demonstrated the ability of the program's flight software to autonomously dock and return to Earth. Boeing did not respond to a media query about why this capability was removed for the crew flight test.
.
It is not clear what change Boeing officials made to the vehicle or its software in the two years prior to the launch of Wilmore and Williams. It is possible that the crew has to manually press an undock button in the spacecraft, or the purely autonomous software was removed from coding on board Starliner to simplify its software package. Regardless, sources described the process to update the software on Starliner as "non-trivial" and "significant," and that it could take up to four weeks. This is what is driving the delay to launch Crew 9 later next month.

Very strange, You normally can update a software program remotely no? I know a spacecraft is a bit more complex than an iPhone, but even if there are , as suggested , physical buttons to press , the spacecraft is accessible so it should be a relatively simple operation . There must be more to the story.

I suspect there isn't a version of software available that is known to be compatible with autonomous operation and the current hardware so they need to run all the performance test cases.

I know that you know, that we know, that they know we know…..NASA will announce this afternoon that Crew-9 is slipping to no earlier than September 24.

"No decisions" have been yet made on when or how of Starliner's return.

Administrator Bill Nelson tells me he will have the final say on how Butch and Suni come home.

In 1959, the Mercury seven demanded a stick be installed in the capsule. It was, but it didn't do anything. Dave is in charge. Tailwinds ...erm, Helium jets

Avweb

So, Messrs Wilmore & Williams, would you like to flag down a passing SpaceX Dragon for your trip home, or be a beta tester for the new software drop on Starliner?

But if the autonomous bit of the software has been removed, how do they get it to undock from the Space Station without an astronaut on board (the Starliner)?

How about designing, implementing and testing the changes a liitle bit before sending them into space? The function to undock automatically was there once, but it had been discarded for a reason (load, memory space etc) and you cannot just copy paste a code into such a complex control system and hope for the best. Any change of a running software bears the possibility of failures. Even Boeing would not do this again:rolleyes:

Final segment of article by Eric Berger:

Port concerns

The International Space Station has two docking ports for crew vehicles, and these must accommodate both Crew Dragon and Starliner. At present, one of these ports is occupied by the Crew-8 spacecraft, which is due to return to Earth fairly soon. The other port is occupied by Starliner. One source at Johnson Space Center said the concern is that NASA cannot afford to "brick" one of its two crew docking ports.

For this reason, if NASA decides to return Starliner autonomously, it must be certain the undocking software update will work.

As NASA is working to balance all of these risks—the risk to crew on board Starliner, the risk of an uncrewed departure to the ISS, the risk to astronauts on board the space station, and more—Boeing has been lobbying to bring Starliner home with crew. Although NASA and Boeing engineers have yet to identify a root cause for the failure of the thrusters, Boeing has been urging NASA to accept "flight rationale" as a substitute. That is, Boeing believes it has provided enough data to NASA to be confident the thrusters will not fail in a catastrophic manner.

This campaign spilled out into the public on Friday evening when Boeing put out a news release [link omitted] trumpeting all of the testing it has done since the launch of the Crew Flight Test.

"Boeing remains confident in the Starliner spacecraft and its ability to return safely with crew," the company stated. "We continue to support NASA’s requests for additional testing, data, analysis and reviews to affirm the spacecraft’s safe undocking and landing capabilities. Our confidence is based on this abundance of valuable testing from Boeing and NASA." [end of article segment]

I'll take a step back, for perspective.

In the Mercury-Gemini-Apollo era, in other words during the "Space Race", the imperative for success was upon NASA on behalf of the country, in the competition begat by the Cold War, and as part of the Cold War, between United States and the U.S.S.R. The competition, really a contestation, involved all the elements of national power - to borrow a phrase from the recently-released Congressional Commission on the National Defense Strategy. This is a significant premise for further points, because the success or failure of any given mission, of each phase of the national effort to send a person (formerly, a "man"), to the Moon and bring the person home safely, was a matter of political accountability within the overall system of government, within the entirety of American society. (Phrasing changes with apologies to JFK's speechwriters for his addresses at Rice University and to Congress which declared the goals of lunar landing and return.)

What accountability has been established for SpaceX, and Elon Musk individually, which would, if it exists, equate to the systemic accountability which existed in the lunar program era? This is not, repeat not, a negative criticism or critique of SpaceX or Musk . . . . so far. That is, so far the company has produced major engineering and programmatic success, perhaps even astounding success. For another time (maybe), what accountability on a par with the kind of national-representational accountability assigned to NASA during the lunar program, has been established for SpaceX with respect to several R&D and operational program elements? For the HLS which is supposed to descend and ascend to/from the lunar surface, matching or exceeding the old, ungainly, but remarkable Lunar Module (LM, or to certain cognescenti, the LEM)? The orbiting fuel depot? And I'm not reaching into my bag of Wishing for Controversy by noting any as-yet unsettled issues with Starlink and Astronomy interference, or orbital debris, or (especially controversy-provoking) how the political consensus in the United States, or Western Alliance countries, or anywhere, resolves contemporary intelligentsia fascination with "settler colonialism" on one hand, and Musk wanting to "colonize" another planet.

So back to Boeing. Ironic, isn't it, that where it once was a major space program contractor - it was part of the Saturn V team iirc - it now stands somewhat apart from NASA? That it appears to be saying to NASA, "trust me, the check is in the mail" whereas in the lunar program era, it bought into, it copped to, the national-representation obligations which had been conferred upon NASA?

The French are correct, the more things change the more they stay the same, but sometimes it takes quite a long process to perceive the changes being made in the first place. Or to understand them. Not to cross threads too much, but maybe experience at Rockwell will help the new CEO get this apparent debacle either clarified as to what really is going on, or straightened out otherwise. In the meantime, DON'T open the pod bay doors HAL.

Really can't see them riding that thing home under a post-challenger NASA. Boeing's rep at the minute isn't going to help that decision process either.
You don't delay a scheduled crew rotation without a very, very good reason....

https://arstechnica.com/space/2024/0...rliner-return/

NASA official acknowledges internal “disagreement” on safety of Starliner return

During a news conference on Wednesday, NASA officials for the first time publicly discussed divisions within the agency about whether the Starliner spacecraft is really reliable enough to return two veteran astronauts—Butch Wilmore and Suni Williams—back to Earth from the International Space Station.

The space agency also confirmed key elements exclusively reported by Ars over the last week, chiefly that NASA has quietly been working for weeks with SpaceX on a potential rescue mission for Wilmore and Williams, that the Crew-9 mission launch has been delayed to September 24 to account for this possibility, and that Starliner is unable to undock autonomously with the current software configuration on the vehicle.

The chief of space human spaceflight operations for NASA, former astronaut Ken Bowersox, said no final decisions have been made on how Wilmore and Williams return to Earth. He said there were reasonable disagreements among engineers at NASA, which is the customer for the spaceflight, and Boeing, which developed and operates Starliner, about the viability of the 28 reaction control system thrusters that are used for delicate maneuvering and pointing of the vehicle.

"I think it's been very healthy," Bowersox said of these internal discussions during a call with reporters on Wednesday. "I have to admit that sometimes when we get disagreement, it's not fun. It can be painful having those discussions, but it's what makes us a good organization."

NASA has been studying various contingencies, but officials appear to have settled on two different options for bringing the two astronauts back to Earth. They could still fly back on Starliner if NASA engineers become more comfortable with the uncertainty about the thruster performance, and if so, they would do so during the second half of this month or the first part of September.

Alternatively, NASA could launch the Crew-9 mission with a complement of two rather than four astronauts, and Wilmore and Williams would join that "increment" on the space station and fly back to Earth in February 2025.

Asked if he thought one of the two scenarios was more likely than the other, Bowersox said he could not say. However, a final decision will be made fairly soon. Bowersox said NASA needs to choose the astronauts' return path by mid-August.

Thruster issues

NASA's concern about Starliner's thrusters boils down to the failure of five of them during the vehicle's ascent to the space station. Starliner's flight computer shut off five thrusters, provided by Aerojet Rocketdyne, in flight. Four of the five thrusters were recovered after overheating.

Since then Boeing and NASA have conducted ground- and space-based tests of the small thrusters to try to replicate the failure and better understand, fundamentally, what is occurring. By getting to the root cause, the engineers will feel confident in their ability to address the problem for Starliner's flight back to Earth.

In ground tests, the engineers were able to demonstrate similar failures. Subsequent inspections showed bulging in a Teflon seal in an oxidizer valve known as a "poppet," which could restrict the flow of nitrogen tetroxide propellant. The thrusters consume the nitrogen tetroxide and mix it with hydrazine fuel for combustion. Despite the tests, however, engineers still don't understand precisely why the bulging is occurring and whether it will manifest on Starliner's flight back to Earth.

"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 and what's causing it to contract," said Steve Stich, who manages the Commercial Crew program for NASA. "That's really what the team is off trying to understand. I think the NASA community in general would like to understand a little bit more of the root cause."

Boeing engineers are advocating for flying Starliner as is, that enough is known about the problem that failures will not occur during the vehicle's return to Earth. However, during meetings of key engineers at NASA known as the "Program Control Board" this week, there was no agreement that this so-called flight rationale was enough to fly crew on the vehicle.

"We heard from a lot of folks that had concerns," Bowersox said. "We heard enough voices that the decision was not clear at the Program Control Board."

Given that NASA will soon decide whether to fly crew on Starliner, the Boeing team has about a week to convince the NASA team of Starliner's safety before a potential switch to Crew Dragon.

Autonomous undock software

Stich also explained why it would take a few weeks to reconfigure the software package on board Starliner to allow for a safe undocking of the spacecraft without crew. This is one reason the Crew-9 mission launch was pushed from August 18 to late September.

Although the capability to undock without a crew exists within the flight software on Starliner, it is currently configured for crew operations. That is, during the process of undocking and moving away from the space station, the flight software takes certain actions, and the crew takes certain actions. This configuration change toward integrated operations between software and crew was made after the previous autonomous flight of Starliner in 2022 that flew to the space station and back.

"Essentially, what we're asking the team is to go back two years in time and resurrect the software parameters that are required to give automatic responses to breakouts near the ISS should we have problem in close to ISS, which the software now allows them to do manually," Stich said. "The team is always updating these mission data loads as different things change."

No work has been done on the autonomous software package since the flight in 2022. Ars reported it would take about four weeks to complete testing of this configuration change, and Stich confirmed this.

"Before we go execute that, it's just smart and responsible to take the software and mission data loads in this configuration, go into the integrated test facility where all the flight software resides, and go run it through some test cases just to make sure we haven't missed anything," Stich said. "That's really what would take the time if we were to pivot to an uncrewed undock."