Boeing’s Starliner spacecraft performed well enough for its maiden astronaut mission that it will likely remain in orbit longer than the 45-day limit originally envisioned, NASA said.
Starliner, launched on June 5, is docked at the International Space Station (ISS) with an indefinite mission extension. The spacecraft is in good condition and is capable of leaving the ISS in case of an emergency. However, NASA and Boeing are trying to understand why some of Starliner’s Reaction Control System (RCS) thrusters experienced problems before docking with the ISS on June 6, and why multiple helium leaks occurred inside the capsule. Therefore, Starliner will remain in space at least until the end of the summer, where tests and analyses will continue. For example, a new round of ground-based thruster tests will start soon, possibly as early as today (July 2).
While an on-orbit test on June 15 failed to find the root cause of the problem, NASA officials highlighted progress on Friday (June 28): The helium leak has been stabilized, and all but one of the failed thrusters are ready for use during the return to Earth. (Starliner’s RCS has a total of 28 thrusters, of which five were faulty, only one of which went offline during undocking.)
The RCS will be housed inside Starliner’s Service Module and will detach before entry, descent, and landing, allowing the team the extra time in orbit to think through how to proceed. This is crucial for design changes to the Service Module that are needed for Starliner’s future six-month ISS rotation mission, which could take place as early as 2025. But to give ground teams time for testing, NASA has said it needs Starliner to stay docked for more than 45 days, which was the original upper limit for the mission. The good news is that the spacecraft can probably fly for twice that long, or even longer, without issue.
Related: A thruster malfunction or helium leak wouldn’t stop Boeing’s Starliner astronaut test flight, but why would this happen?
“We’ve discussed the 45-day limit imposed by the batteries in the Starliner crew module, and we’re in the process of updating that limit,” Steve Stich, NASA’s commercial crew program manager, told reporters during a conference call Friday.
“We’ve studied these batteries and their performance in orbit. The batteries are being recharged on station and the risk hasn’t really changed. So the risk over the next 45 days is essentially the same as it was in the first 45 days,” he said.
In fact, he noted, Starliner is rated to stay in orbit for up to 210 days once its operational mission begins, but because this is Starliner’s third mission in space and its first to carry astronauts, NASA was previously unsure about how the batteries would perform in orbit.
When asked by Space.com how long the mission will last, Stich said, “We haven’t decided yet on the extension period.” He explained that Starliner has 12 different batteries on board. Prior to this flight, similar batteries were grounded for a year and tested to ensure they were free of defects, but none were found.
“What we’re actually doing right now is looking at the performance of the batteries in flight, and we’re not seeing any degradation in any of the cells that are on board,” he added.
The current Starliner mission, called Crew Flight Test (CFT), was originally scheduled to last about 10 days and includes two NASA astronauts, Butch Wilmore and Suni Williams, both former U.S. Navy test pilots with decades of experience on development missions like this one.
Wilmore told Space.com on May 1, ahead of the launch, that the Navy had equipped the astronauts with skills highly relevant to the CFT, such as testing how systems work together. “Well, that’s really why we’re here,” Wilmore said, recalling the pair’s thousands of hours of piloting experience. Wilmore later added that their experience was “invaluable to the process” in working on Starliner.
The CFT is designed to explore unexpected events in space, with flexibility built into the schedule. Additional ground tests will be conducted at the White Sands Test Facility in New Mexico and will attempt to replicate how the RCS thrusters were used in flight, particularly during docking. (NASA rejected the first docking attempt on June 6, but approved a second docking a few hours later.)
Meanwhile, Williams and Wilmore have been supporting ISS astronauts with other tasks while they await the results of the White Sands test, which will take at least two weeks. A recent NASA blog post detailed how CFT astronauts have been busy with ISS maintenance tasks, including on-orbit plumbing for a few days and, more recently, organizing items inside the Permanent Utility Module.
Williams and Wilmore also worked aboard the Japanese Laboratory Module on Monday (July 1), “disassembling the empty Nanorack CubeSat deployment assembly in preparation for upcoming Nanorack missions.” A NASA official wrote: Monday (July 1st)
Starliner’s first two space missions were unmanned. The first, in December 2019, failed to reach the ISS after a computer glitch left it in the wrong orbit. The second, in May 2022, successfully reached the ISS after dozens of corrections by Boeing, but the Starliner’s thrusters experienced some problems. This is another reason why NASA and Boeing are taking their time with the CFT’s return and are investigating why the spacecraft’s thrusters malfunctioned in both 2022 and 2024.
Boeing is one of two suppliers for astronaut missions to the ISS, the other being SpaceX. Elon Musk’s company uses the Crew Dragon capsule, which is based on SpaceX’s Dragon cargo plane. Crew Dragon got to orbit more quickly; it conducted one uncrewed mission in 2019, followed by a test flight with astronauts in 2020. Since then, Dragon has delivered 11 crew members to the ISS, most of whom have been part of NASA’s six-month operational crew rotation missions.