The docking was originally scheduled for 7:10 p.m., but was delayed due to a controller on the ground checking the telemetry data, ensuring that lighting conditions were ideal and communication was stable. Docking was delayed again after a problem with the mechanism the Starliner uses to dock with the station forced the controller to deflate the system and then expand it again to reset it.
On the way to the station, two of the Starliner’s 12 main thrusters failed shortly after launch, and the spacecraft’s temperature control system also malfunctioned. However, no issues prevented docking and the thrusters worked fine during post-launch maneuvers. Place it where you want to dock it.
Boeing blamed the thruster problem for the pressure drop in the thruster chamber. However, the company also said the capsule’s flight control system automatically fired a third thruster as a backup, completing the burn.
At a post-docking briefing with reporters, Steve Stich, NASA’s commercial crew program manager, said there were also problems with the two small thrusters used to position the spacecraft for docking. “We have a lot of redundancy, so it doesn’t really affect the rendezvous work at all or the rest of the flight,” he said. “When the flight is over, I’ll study the failure there and see what happened.”
Mark Nappi, Boeing’s vice president overseeing the Starliner program, said it was “a good day” for the company and NASA to have another spacecraft that could send astronauts to a station. The vehicle won’t sit there for a while until it’s time to come in. So thanks to what we’ve seen, there are a lot of very happy people in the Boeing program today.”
He said it’s not entirely clear what’s causing the pressure drop problem, and since the thruster is in a service module that gets scrapped during the return flight, “You’ll never know what the real cause of this problem is. “
Boeing also said it is continuing to monitor for problems with thermal control systems designed to keep the capsule’s system at the proper temperature as it passes through the vacuum of space. Spokesperson Steve Siceloff said during the docking live broadcast that the company was able to overcome the problem by “manually adjusting the cooling system, which is usually automated.”
“It’s all part of the learning process to get the Starliner into orbit,” he said.
Boeing said in a statement that the spacecraft “continues to work well.”
Flights are tests that NASA checks to see how a vehicle will perform before allowing astronauts to fly. Boeing has been working to complete the flight since 2014, when NASA signed a contract with Boeing and SpaceX to develop a spacecraft that could take astronauts to the space station and return them.
SpaceX made a crewless test flight in March 2019 and has since performed five missions with NASA astronauts, four of which are full with four crew members.
In contrast, Boeing stumbled repeatedly. In its first attempt at an unmanned test flight, the spacecraft suffered software and communications issues that disrupted the mission before rendezvous with the station. It took 18 months for the company to try again, but the flight didn’t even take off from the ground when engineers discovered in August that 13 valves on the service module were stuck in the closed position.
Boeing says it has fixed an issue that occurs when propellant seeps through the valve and mixes with ambient moisture, causing corrosion.
Regarding docking on Friday, the company said the capsule’s systems such as guidance and navigation, flight software, communications and power generation are all performing well.
The capsule is expected to remain docked at the station for four to five days before returning to Earth.
If all goes well, Boeing and NASA will have crews on the vehicle for the first time later this year or early next year.