NASA, Boeing delay Starliner astronaut landing to June 26 amid thruster issues

Boeing's white and blue Starliner spacecraft docked at the International Space Station in June 2024.
Boeing's white and blue Starliner spacecraft docked at the International Space Station in June 2024. (Image credit: NASA)

The return to Earth of Boeing's Starliner capsule will be delayed a few more days due to thruster troubleshooting and a scheduled spacewalk.

NASA announced today (June 18) that Starliner will conclude its first human mission to the International Space Station (ISS) no earlier than June 26, nearly three weeks after it launched. Landing that day is scheduled to occur at White Sands Space Harbor in New Mexico at 4:51 a.m. EDT (0851 GMT). We'll carry it live here at, via NASA Television.

The two-astronaut mission, known as Crew Flight Test (CFT), was originally supposed to spend about a week at the ISS, but its ISS departure has been pushed back considerably. NASA and Boeing are using the extra time to continue evaluating thruster issues that interfered with Starliner's first ISS docking attempt on June 6. Additionally, a postponed ISS maintenance spacewalk will now take place on June 24, two days before Starliner's scheduled departure.

"We want to give our teams a little bit more time to look at the data, do some analysis and make sure we're really ready to come home," Steve Stich, manager of NASA's Commercial Crew Program, said during a livestreamed teleconference with reporters today. Starliner can undock in case of emergency, but otherwise, testing is ongoing to learn more about the vehicle's systems.

Related: Thruster glitches and helium leaks can't stop Boeing's Starliner astronaut test flight — but why are they happening?

Stich reiterated that five of Starliner's 28 reaction control thrusters failed during the final phase of the ISS rendezvous on June 6, though four of them eventually came back online. (Starliner succeeded on its second docking try, which occurred several hours later on June 6.) Evaluation of what happened is ongoing. As part of that effort, Boeing and NASA ground team members performed a thruster hot-fire test over the weekend alongside the astronauts, and, after that, Stich said, everyone "feels very confident." 

One thruster was not fired during the test due to abnormally low pressure first observed during docking, and it will remain offline during the return to Earth. (Canadarm2, the robotic arm on the space station, was also used to view the thrusters via robotic camera, according to ISS Program Manager Dana Weigel, who also participated in the teleconference.)

CFT's docking was a bit more complex than the only other time Starliner approached the ISS, which was done during an uncrewed test flight in May 2022. That uncrewed mission, called Orbital Flight Test 2 (OFT-2), also faced thruster issues that interfered with docking.

But "the rendezvous [for CFT] was a little bit more demanding on the propulsion system. In other words, it fired its thrusters a bit more frequently," Stich said. Additionally, teams are doing hardware simulations at NASA's Marshall Space Flight Center in Alabama to model ongoing helium leaks on Starliner.

Boeing's Starliner during its final approach to the International Space Station on June 6, 2024. (Image credit: NASA)

A small helium leak in one of Starliner's reaction control system (RCS) thrusters was first discovered on the pad in early May, after a launch attempt was waved off due to a valve issue with the capsule's United Launch Alliance Atlas V rocket. 

Several new helium leaks arose during the mission, and a fault tree analysis is ongoing to find out what happened. Stich said the helium leaks and RCS thruster issues appear to have different causes, while Mark Nappi, vice president and program manager of Boeing's commercial crew program, said data review is continuing to reveal more about what is happening.

The helium leak on the launch pad was not an immediate safety issue, but in investigating it further, NASA and Boeing uncovered a design vulnerability in the RCS system that could affect Starliner's reentry. Agency officials subsequently certified a new reentry mode after testing the idea on the ground in simulations with the CFT crew, veteran NASA astronauts Barry Wilmore and Suni Williams, both of whom are former U.S. Navy test pilots.

NASA astronauts Suni Williams (left) and Butch Wilmore, the first people to fly on Boeing Starliner, are the two astronauts of Crew Flight Test. (Image credit: NASA/Frank Micheaux)

Wilmore and Williams have been testing Starliner's various systems in orbit, and ground teams have continued to analyze data to get a better handle on the thruster and helium-leak issues.

Stich emphasized that testing in orbit on Saturday (June 15) gave the team confidence that Starliner is recovering. "Saturday was a big day of understanding that helium leaks have gone down, and also understanding the thrusters have recovered, and that we can count on the thrusters for the remainder of the flight," he said.

Although evaluation of what is happening continues, he said the tone of the conversation has changed. "I think now we're doing the normal business we do of, What are the contingencies that could happen [with] the undock timeframe? And when we get to these, how we manage each of those contingencies, should something happen, and then look at the procedures we have in place. Are we ready to execute those?"

The delayed mission return also accommodates a planned June 13 spacewalk that was postponed due to a "spacesuit discomfort" issue during suit-up. NASA astronaut Matt Dominick, the ISS crew member experiencing discomfort, will not go outside during the rescheduled spacewalk on June 24 to prevent this from happening again, Weigel said during today's press conference.

Weigel told that, if the June 24 spacewalk is delayed again, Starliner's undocking would be the priority and spacewalking NASA astronauts Tracy Caldwell Dyson and Mike Barratt would wait until after Starliner leaves to perform the extravehicular activity.

Boeing's Starliner launches to space atop a United Launch Alliance Atlas V rocket on June 5, 2024. (Image credit: Joe Raedle/Getty Images)

CFT is a developmental mission. Throughout the launch and flight campaign, Boeing and NASA have emphasized that mission timelines are therefore very much in flux as Starliner flies its first-ever mission with humans on board. Wilmore and Williams said much the same, based on their experience with the U.S. Navy flying complex aircraft.

"We've always said this is a test flight, and we're going to learn some things. So here we are," Nappi said during today's press conference. "We've learned that our helium system is not performing, albeit manageable. It's still working like we had designed it. So, we got to go figure that out."

Nappi emphasized that the performance of most of the RCS thrusters is good, trending toward nominal, while the helium leaks "show that they're stable and less than measured [before]." The team is working to learn more about Starliner while the service module, which provides most of the spacecraft's fuel and power, is still attached to the spacecraft, as it will be discarded just before landing.

"This is an opportunity to fully understand the system's performance and without the pressure of schedule or time," Nappi said. Aside from the technical issues, the mission has satisfied 77 of the original 87 flight test objectives, he noted; the remaining 10 will be evaluated during undocking and landing.

Related: NASA weighs potential impacts of helium leaks and more on Boeing's Starliner astronaut test flight

Boeing's Starliner capsule is seen docked to the International Space Station in this zoomed-in view of an image captured by Maxar Technologies' WorldView-3 satellite on June 7, 2024. (Image credit: Maxar Technologies)

Starliner, along with SpaceX's Dragon capsule, are tasked by NASA to send agency-led crews to the ISS from American soil. (Russia also leads and launches cosmonaut-led crews on its long-running Soyuz spacecraft.) CFT aims to certify Starliner for the first operational ISS rotation mission, called Starliner-1, expected to launch in 2025.

Dragon and Starliner were first tasked in 2014 to send NASA astronauts aloft by 2017, but funding and technical issues extended the timeline by several years. SpaceX, whose Crew Dragon spacecraft is based on the company's ISS cargo capsule, launched its first astronaut test mission in 2020 following just one uncrewed test flight. Starliner's first human mission came four years after that and required two uncrewed tests, in part because the spacecraft is a new design.

Starliner's path to CFT was delayed after the capsule experienced problems on its first uncrewed test mission in December 2019 and failed to reach the ISS as planned. (Astronauts often say, however, that in developmental programs such as Starliner, timelines are difficult to estimate as the unexpected can always arise.)

Boeing addressed those glitches, which took time. The outbreak of the coronavirus pandemic in early 2020 delayed the launch of the second uncrewed ISS mission further, pushing it into May 2022. CFT was next expected to launch in 2023, but that flight was delayed after issues with parachute loading and flammable tape were uncovered last year.

CFT then underwent two scrubs on the pad due to issues with the Atlas V and ground equipment. The first, on May 6, occurred roughly two hours before launch due to a "buzzing valve" that required rolling back to a company facility for replacement. The second launch attempt on June 1 was scrubbed due to an issue with a ground launch sequencer less than four minutes before liftoff.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon:

  • Unclear Engineer
    Remember that these 2 astronauts had their changes of clothing confiscated to offset the weight addition of the replacement pump for the urine recycling apparatus. So, now it's 3 weeks in the same clothes? Or did they get some "loners" while on the ISS.

    And, please tell us if the urine recycling system has been fixed by now.
  • newtons_laws
    Unclear Engineer said:
    Remember that these 2 astronauts had their changes of clothing confiscated to offset the weight addition of the replacement pump for the urine recycling apparatus. So, now it's 3 weeks in the same clothes? Or did they get some "loners" while on the ISS.

    And, please tell us if the urine recycling system has been fixed by now.
    Good point about not bringing clothes for a 3 week stay, hopefully there may be some on the ISS that can be loaned to them (assuming they fit :tearsofjoy: ). Talking of which do they have a washing machine on the ISS, I guess not, it might be tricky in zero g. ;) I suppose dirty clothing is just put into the garbage for disposal when an old cargo ship burns up in the atmosphere on re-entry.
  • Unclear Engineer
    Correct, no washing machines and dirty clothes are burned up on reentering cargo ships.

    But, there is some interest in developing space washing machines. See .
  • mcswell
    Unclear Engineer said: it's 3 weeks in the same clothes? Or did they get some "loners" while on the ISS.
    If they are still wearing the same smelly clothes, then I guess those two astronauts are loners... unless they got loaners, that is.
  • Unclear Engineer
    Spell check doesn't catch everything.
  • newtons_laws
    Delayed again until 2nd July at the earliest..... :rolleyes:
  • Unclear Engineer
    Delayed with no new date specified.

    Unlike previous delays, the July 2 date is just the date of a space walk that would interfere with Starliner departure. There is no planned date for Starliner to leave at this point.

    “We are taking our time and following our standard mission management team process,” Steve Stich, NASA commercial crew program manager, said in the 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.”

    NASA now plans to carry out an agency-level review of Starliner before its departure.

    So, this situation does not seem to be as "worry free" as the publicity would imply.