Boeing Starliner hatch closed, stage clear for unmanned return to Earth on Friday

As the troubled mission finally came to an end, Boeing’s Starliner capsule was prepared for re-entry and its hatch closed on Thursday, setting the stage for undocking and an unmanned return to Earth on Friday night in the final chapter of a disappointing Test flight.

Ninety-two days later Start Aboard the Starliner – a mission originally scheduled to last just over a week – Commander Barry “Butch” Wilmore and co-pilot Sunita Williams kept their thoughts to themselves as the hatch closed at 1:29 p.m. EDT.

Leaving Wilmore and Williams behind, the Starliner is expected to undock from the International Space Station's forward Harmony module shortly after 6 p.m. Friday. Five hours and 15 minutes later, the spacecraft's powerful braking rockets are programmed to fire for about 59 seconds to deorbit the ship.

After a rapid southwest-to-northeast dive over the Baja California Peninsula, the Gulf of California and northern Mexico, the Starliner is expected to descend on its three main parachutes shortly after midnight and touch down at an airbag-assisted speed of 4 mph (6.4 kph) in White Sands, New Mexico, where recovery teams from Boeing and NASA will stand by.

Return of astronauts delayed until February

Wilmore and Williams will Return to Earth next Februaryand will be brought home aboard a SpaceX Crew Dragon shuttle scheduled for launch on September 24. When they finally return next year, they will have spent 262 days in space.

On Wednesday, as she worked inside the Starliner, helping to arrange return items to ensure proper balance and center of gravity, Williams said, “It's bittersweet to pack up the Starliner and put our simulators in our seats. But you know, we want to do our best to make sure it's in good shape.”

She assured air traffic controllers: “We'll be cleaning everything up tomorrow (Thursday), making sure everything is OK and doing a few final things to finish before the hatch closes. Thank you for your support, thank you for looking over our shoulders and making sure everything is in the right place. We want her to have a nice, soft landing in the desert.”

When Williams and Wilmore have taken off They boarded the Starliner on June 5, expecting to be at the helm when the ship returned to Earth to complete its first crewed test flight. Boeing was equally confident that the ship would be certified to carry long-duration crews to and from the space station starting in early 2025.

But during the rendezvous with the space station the day after launch, the Starliner experienced several helium leaks in the propulsion pressure system and five maneuvering thrusters were “deselected” by the onboard computer after they showed reduced thrust.

Boeing and NASA then began a comprehensive series of tests and analyses to determine the cause of the problems and whether they could potentially worsen or otherwise jeopardise safe reentry and a scheduled landing.

Based on the test data, Boeing engineers concluded that the problems were known, would not worsen, and that Starliner could return Wilmore and Williams safely to Earth. They argued that the departure and reentry maneuvers would be much less stressful than what the engines experienced during rendezvous.

But those thrusters are critical. They must fire when needed to move the Starliner safely away from the space station and then keep it properly aligned and stable during the firing of the deorbit rocket that will take the ship out of orbit.

In the end, NASA managers did not accept Boeing’s flight justification and decided too much uncertainty remained risking causing Wilmore and Williams to crash aboard the Starliner.

“We look at the data and the uncertainties associated with it differently than Boeing,” said NASA Deputy Administrator Jim Free.

While other, more powerful engines are used for the actual braking effect, the smaller reaction control thrusters are needed to ensure that the ship stays on the correct trajectory to reach the White Sands landing site.

“Spaceflight is difficult. The boundaries are tight. The space environment is not unforgiving,” said Norm Knight, flight operations manager at Johnson Space Center. “And we have to be right.”