Two veteran astronauts will extend their stay on the International Space Station as teams on the ground work to better understand issues with the Boeing-built spacecraft that carried them to orbit.
Boeing and NASA officials said Tuesday that Suni Williams and Butch Wilmore — who arrived at the space station on June 6 for what was estimated to be roughly a weeklong visit — will not return home before June 26.
That target date marks a delay from earlier projections of June 18 and June 22.
Since launching to orbit June 5 on the first crewed test flight of Boeing’s Starliner spacecraft, the astronauts have navigated a number of issues with the vehicle — including malfunctioning thrusters and a series of helium leaks that sprung up en route to the space station.
Keeping the vehicle in orbit is essential to studying the issues, which occurred on the Starliner spacecraft’s service module — a cylindrical attachment that sits at the bottom of the spacecraft. The service module will be jettisoned and discarded as the capsule returns home from space.
Because the service module won’t be returning with the mission, engineers will not have an opportunity to gather more data about the technical problems after the astronauts land, noted Steve Stich, NASA’s Commercial Crew Program manager, at a Tuesday news conference.
That’s why they’re are hoping to learn as much as possible while the vehicle is still docked at the space station, but none of the problems have yet threatened the overall success of the mission, Stich said.
“So far, we don’t see any scenario where Starliner is not going to be able to bring Butch and Suni home,” Stich said.
“We really want to work through the remainder of the data,” he added.
An eventful test mission
The launch of Starliner’s inaugural astronaut flight came after years of delays and development hangups, including a list of problems with the spacecraft’s software and propulsions system revealed by two uncrewed test missions in 2019 and 2022.
The Starliner’s current troubles suggest the development team did not resolve all those issues before the crewed flight.
Similar thruster issues, for example, were revealed during the spacecraft’s 2022 uncrewed test flight.
Stich acknowledged during a June 6 news conference that officials “thought we had fixed that problem.”
But, he added, “I think we’re missing something fundamental that’s going on inside the thruster.”
Since the June 6 docking, NASA and Boeing officials have worked to review flight data and analyze the problems, a process that’s ongoing, Stich said. It’s possible that the thruster issues may be caused by overheating that affected how the thrusters’ fuel burned as they fired rapidly during Starliner’s rendezvous with the space station, he added.
It is not yet clear what may have caused the helium leaks, though that problem could also be related to the thruster issues, officials said.
In total, there are 28 reaction control thrusters on Starliner’s service module and 12 on the Starliner vehicle itself, according to a Boeing fact sheet. When asked during the news briefing, Stich did not say how many of those thrusters might fail before the Starliner is deemed unsafe.
Of the five service module thrusters that failed during flight, all but one have been recovered, officials said.
If the current timeline sticks, Williams and Wilmore could climb aboard the Starliner capsule and undock from the space station just after 10 p.m. ET on June 25, before parachuting to a landing shortly before 5 a.m. ET on June 26.
The next opportunity to leave the space station after that would be July 2, Stich noted, with additional chances for departure occurring every four days.
“I think we’re taking our extra time, given that this is a crewed vehicle, and we want to make sure that we haven’t left any stone unturned,” Stich said.
