Boeing's Starliner has left the International Space Station and is making its way back to Earth for a landing in the New Mexico desert.

NASA astronauts Suni Williams and Butch Wilmore could do little more than watch from the orbital outpost as the spacecraft that brought them there in June undocked autonomously and departed without them. About two weeks ago, NASA made the call to scuttle the pair of astronauts' return to Earth on Starliner, determining that Boeing's troubled capsule was not reliable enough to bring them home.

Instead, Starliner is now making a journey back to the ground without its crew, who are scheduled to remain at the space station for another five months and return in February aboard a SpaceX vehicle.

"OK, she's on her way home," Williams said on the livestream of the undocking. "Congratulations to the undock team."

Despite NASA's hesitancy to send Williams and Wilmore home on Starliner, agency officials expressed confidence that the spacecraft's landing should go off without a hitch. Ahead of the Starliner is a venture that should last a few hours before an anticipated landing early Saturday using parachutes to slow its fall.

“We have confidence in the vehicle,” Steve Stich, the manager of the commercial crew program at NASA, said during a Wednesday news conference. “It’s been a journey to get here, and we’re excited to have Starliner undock and return."

Starliner undocks from space station, heads for Earth

The uncrewed spacecraft departed from the station at 6:04 p.m. ET in a process that took five minutes to complete. NASA streamed the successful undocking, capturing the light show that appeared as 27 jets fired.

At 6:11 p.m. ET, all 12 breakout burn firings completed successfully crossing the ISS's Keep Out Sphere as planned.

The spacecraft is set for perfect trajectory where it drop out of orbit and pass the Pacific Ocean across Baja California before landing at the New Mexico space harbor.

Using thruster burns, the Boeing capsule autonomously steered itself away from the space laboratory and toward Earth to begin its descent into the atmosphere. The entire trip is expected to take a few hours before the uncrewed vehicle lands around 12:03 a.m. Saturday at White Sands Space Harbor in New Mexico.

Boeing has work ahead if Starliner is to be certified

The anticipated landing would bring to a conclusion the first crewed test flight of Boeing's Starliner, which had encountered troubles even before liftoff.

A series of mission scrubs delayed Starliner's launch for about a month until June 5, when it was finally able to take off from the Kennedy Space Center in Florida atop an Atlas V rocket. When the capsule made it to the orbital outpost a day after the launch, engineers discovered a slew of helium leaks and problems with the craft's propulsion system that hampered Starliner's return.

Boeing officials had high hopes that a successful mission would be the demonstration needed to win approval from NASA for Starliner to join SpaceX in making routine trips to orbit on behalf of the U.S. space agency.

But now, Boeing has its work cut out for it to get Starliner up to the task of regularly transporting crews and cargo to the space station. Ahead of the aerospace company are more ground tests and potential modifications to the vehicle to remedy its propulsion system woes and prepare it for routine spaceflight, NASA officials said Wednesday.

Meanwhile, Elon Musk's SpaceX has already begun reliably transporting astronauts and supplies since 2020 to the space station aboard its Dragon.

NASA shelled out billions of dollars to both Boeing and SpaceX to develop the vehicles as part of its commercial crew program. In recent years, the agency has shifted to paying private companies for missions it once would carry out itself as a way to cut costs.

Wilmore, Williams to return with SpaceX in February

As for Wilmore and Williams, they'll have no choice but to remain at the space station for another five months, barring any changes to NASA's outlined plan.

That's of course much longer than the 10 days that the pair of astronauts were originally scheduled to be at the space station before they were slated to return aboard the Starliner. But NASA officials have insisted that the veteran astronauts, who have each been to space twice before, were trained and prepared for the possibility of an extended mission.

As it stands, the plan now is for Wilmore and Williams to return in February on a SpaceX Dragon vehicle that will launch to reach the station as early as Sept. 24. The Dragon, which was initially scheduled to bring a full contingent of four Crew-9 astronauts, will instead bring just two so that the Starliner crew have room to hitch a ride home, NASA has said.

The Boeing spacesuits that Wilmore and Williams wore on their way to orbit will return with Starliner. A SpaceX suit is already available for Williams to wear on the return journey, while Crew-9 will launch with an extra suit for Wilmore, Stich said Wednesday.

The Crew-9 astronauts are to relieve the Crew-8 mission to begin a six-month rotation at the space station, which is why Wilmore and Williams cannot return sooner.

During their stay, Williams and Wilmore have joined Expedition 71 in conducting more than 40 scientific experiments aboard the station already, said Dana Weigel, the program manager for the space station at NASA. Until they return next year, the astronauts will continue to help with scientific research and routine maintenance.