Boeing Co.'s (NYSE:BA) Starliner is slated to undock from the International Space Station (ISS) without a crew later today after NASA decided to return the two astronauts who went to space aboard the spacecraft later on a SpaceX vehicle.

What Happened: The decision to return Boeing's Starliner spacecraft without a crew was a "tough" one, manager of NASA's Commercial Crew Program Steve Stich said on Wednesday.

There was "some tension" in the last meeting between Boeing and the space agency on the decision, Stich said while adding that he would not characterize it as "heated."

Boeing believed in its spacecraft's ability to return the astronauts safely but the NASA team found "limitations" on the company's modeling on thruster degradation for the remaining flight, Stich said.

"I wouldn't say it was a yelling, screaming kind of a meeting. It was a tense technical discussion where we had both sides listening intently to all the data and in the end make a decision whether to return crewed or uncrewed...," Stich said.

Why It Matters: Last month, NASA announced that it would return Sunita Williams and Butch Wilmore via a SpaceX vehicle in February.

The two astronauts launched into space on June 5 aboard Starliner. Though the two were supposed to return in about eight days, technical issues identified with the spacecraft while docking, including helium leaks and issues with the spacecraft reaction control thrusters, delayed the return journey, and the agency subsequently decided to scrap bringing the astronauts back on the Boeing spacecraft altogether.

The two will now return with Crew-9 astronauts in February. Crew 9 mission will launch to the space station no earlier than Sept. 24 with just two astronauts, instead of four as previously planned, to make space for Williams and Wilson on the return journey.

The Starliner is now slated to undock from the space station on Sept. 6 at about 6 p.m. EDT and land at White Sands Space Harbor in New Mexico at about 12:03 a.m. on Saturday, Sept. 7.

Starliner's return is expected to be safe and uneventful as the spacecraft has previously completed a successful uncrewed entry and landing as part of its previous flight tests.

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