by The return to Earth of the Boeing Starliner capsule will be delayed by a few more days due to thruster troubleshooting and a scheduled spacewalk.
NASA announced today (June 18) that Starliner will complete its first human mission to the International Space Station (ISS) no earlier than June 26, nearly three weeks after launch. The landing that day is scheduled to take place at White Sands Space Harbor in New Mexico at 4:51 am EDT (0851 GMT). We’ll be launching it live here at Space.com, via NASA Television.
The two-astronaut mission, called Crew Flight Test (CFT), was originally supposed to spend about a week at the ISS, but its ISS departure has been pushed back significantly. NASA and Boeing are using the extra time to continue evaluating thruster issues that disrupted Starliner’s first ISS landing attempt on June 6. In addition, the postponed ISS maintenance spacewalk will now take place on June 24, two days before Starliner’s scheduled departure.
“We want to give our crews a little 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 teleconference streamed live with reporters today. Starliner can unlock in an emergency, but otherwise, testing is underway to learn more about the vehicle’s systems.
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Stich reiterated that five of Starliner’s 28 reaction control thrusters failed during the final phase of the ISS rendezvous on June 6, although four eventually came back online. (Starliner was successful in its second docking attempt, which occurred several hours later on June 6.) An assessment of what happened is underway. As part of that effort, Boeing and NASA ground crew members conducted a thruster fire test over the weekend with the astronauts, and, afterward, Stich said, everyone feels “very confident.”
One thruster did not fire during the test due to too low pressure initially observed during combustion, and will remain offline during return to Earth. (Canadam2, the robotic arm on the space station, was also used to view the asteroids through a robotic camera, according to ISS Program Manager Dana Weigel, who also participated in the teleconference.)
CFT docking was a bit more complicated than the only other time Starliner touched down with the ISS, which was during an uncrewed test flight in May 2022. That uncrewed mission, called Orbital Flight Test 2 (OFT- 2), facing thruster issues that also affected. with a dock.
But “the rendezvous [for CFT] the drive system was a bit tougher. In other words, it fired its thrusters a little more often,” Stich said. Also, teams at NASA’s Marshall Space Flight Center in Alabama are doing hardware simulations to model a continuous leak of helium on Starliner .
A small helium leak in one of the Starliner’s reaction control system (RCS) thrusters was first discovered on the pad in early May, after a launch attempt was aborted due to a valve issue with a United Launch rocket Alliance Atlas V the capsule.
Several new helium leaks emerged during the mission, and a fault tree analysis is underway to determine what happened. Stich said the helium leak and RCS thruster issues appear to have different causes, and Mark Nappi, Boeing’s vice president and commercial crew program manager, said a data review continues to reveal more about what happening.
The helium leak on the launch pad was not an immediate safety issue, but during further investigation, NASA and Boeing uncovered a design vulnerability in the RCS system that could affect Starliner’s re-entry. Agency officials later confirmed the new reentry method after testing the idea on the ground in simulations with the CFT crew, veteran NASA astronauts Barry Wilmore and Suni Williams, both former Navy test pilots. United.
Wilmore and Williams have been testing various Starliner systems in orbit, while ground crews have continued to analyze data to get a better handle on the thruster and helium leak issues.
Stich emphasized that an in-orbit test on Saturday (June 15) gave the team confidence that Starliner is recovering. “Saturday was a big day realizing that the helium leak has gone down, and also realizing that the thrusters have come back on, and that we can rely on the thrusters for the rest of the flight,” he said.
While evaluation of what is happening continues, he said the tone of the conversation has changed. “I think now that we are doing the usual business, What events could happen [with] the undock time frame? And when we achieve these, how do we manage each of those incidents, 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 an “uncomfortable spacesuit” issue during suit-up. NASA astronaut Matt Dominick, the ISS crew member who is in 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 Space.com that if the spacewalk was delayed again on June 24, Starliner’s disposal would be the priority and that NASA astronauts Tracy Caldwell Dyson and Mike Barratt would wait until Starliner leaves to perform the extravehicular activity.
CFT is a development mission. During the launch and flight campaign, Boeing and NASA have emphasized that mission timelines are 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 US 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, even though it’s manageable. It’s still working the way we designed it. So, we had to figure that out.”
Nappi emphasized that the performance of most RCS detectors is good, approaching nominal, and the helium leaks “show that they are stable and smaller than measured.” [before].” The team is working to learn more about Starliner even though the service module, which provides most of the spacecraft’s fuel and power, is still attached to the spacecraft, as it will be jettisoned just before landing.
“This is an opportunity to fully understand the performance of the system without the pressure of schedule or time,” said Nappi. Aside from the technical issues, the mission has met 77 of the original 87 flight test objectives, he noted; the remaining 10 will be assessed during undocking and landing.
Related: NASA weighs possible impact of helium leak and more on Boeing Starliner astronaut test flight
Starliner, along with SpaceX’s Dragon capsule, is tasked with sending agency-led crews to the ISS from American soil. (Russia also leads and sends cosmonaut crews on its long-running Soyuz spacecraft.) CFT aims to certify Starliner for the expected first operational ISS orbiting mission, called Starliner-1 to be launched in 2025.
Dragon and Starliner were first tasked in 2014 with launching NASA astronauts by 2017, but funding and technical issues have delayed the timeline for several years. SpaceX, whose Crew Dragon spacecraft is based on the company’s ISS cargo capsule, launched its first astronaut test mission in 2020 after a single unmanned test flight. Starliner’s first human mission came four years later and required two uncrewed tests, in part because the spacecraft was a new design.
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Starliner’s path to CFT was delayed after the capsule encountered problems on its first uncrewed test mission in December 2019 and failed to reach the ISS as planned. (Astronauts often say, however, that in development programs like Starliner, it’s difficult to estimate timelines because the unexpected can always come up.)
Boeing addressed those glitches, which took time. The outbreak of the coronavirus pandemic in early 2020 further delayed the launch of the second uncrewed ISS mission, pushing it into May 2022. CFT was expected to launch in 2023, but that flight was delayed after issues with parachute loading and flammable tape being exposed. 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 about two hours before launch due to a “buzzing valve” that required a roll back to a company facility for replacement. A second launch attempt on June 1 was scrapped due to an issue with the ground launch sequencer less than four minutes before liftoff.
