This time, can the Boeing Starliner finally shine?

Enlarge / Boeing says its Starliner spacecraft is ready to taxi to the launch pad in Florida.


Boeing and NASA say the Starliner spacecraft is ready for a resume flight, with the spacecraft’s second uncrewed test mission now scheduled for May 19.

Nine months have passed since a standard pre-flight check of the spacecraft, while sitting atop a rocket on a Florida launch pad, revealed that 13 of the 24 oxidizer valves in Starliner’s propulsion system were blocked. The discovery was made a few hours after takeoff.

Since then, Boeing and NASA engineers and technicians have worked to fully understand why the valves were stuck and to resolve the problem. They found that the nitrogen tetroxide oxidizer that had been loaded onto the spacecraft 46 days before launch had combined with ambient humidity to create nitric acid, which started the corrosion process at inside the valve’s aluminum housing.

During a conference call with reporters on Tuesday, Boeing and NASA officials discussed steps they have taken to address the issue of Starliner’s upcoming test flight. Michelle Parker, vice president and deputy general manager of Boeing Space and Launch, said the valves remain the same on the vehicle, but technicians have sealed the pathways through which moisture could enter inside the system. propulsion. They also purge moisture from the valves using nitrogen gas and load propellants onto Starliner closer to launch.

With these mitigations undertaken, Starliner will soon be stacked on an Atlas V rocket built by United Launch Alliance. Starliner was actually scheduled to roll out to the Atlas V launch complex in Florida on Wednesday, but Boeing said the deployment was “suspended” due to a hydraulic leak on the United Launch Alliance transport vehicle.

So it goes hand-in-hand with Boeing’s start-and-stop efforts to get Starliner into service. The company has been working on the vehicle since at least 2010, when it was called Crew Space Transportation-100, or CST-100. Starliner made its first flight in December 2019, but problems arose just minutes after liftoff, when the spacecraft captured the wrong “mission elapsed time” from its Atlas V launch vehicle. It also had trouble communicating with ground stations. NASA and Boeing flight controllers were able to restore communications with Starliner and help it reach orbit. However, due to expended propellant during these activities, Starliner was unable to fulfill its primary purpose, demonstrating safe docking with the International Space Station.

There were also problems on the return trip to Earth. Another software error, detected and corrected just hours before the vehicle returned to Earth through the atmosphere, reportedly caused Starliner’s service module thrusters to fire incorrectly. The vehicle was almost lost a second time.

These issues led NASA to declare Starliner’s first test flight a “high-visibility close call” and to launch a years-long investigation and in-depth analysis of Starliner’s software issues. Boeing agreed to pay for a second test flight at a cost of 410 million dollars and finally prepared the Orbital Flight Test-2 mission which reached the pad in the summer of 2021. Then the vehicle had its problem of sticky valve. Finally, after all of that, the company has put Starliner back on the carpet, ready for a redesign launch redesign.

NASA, of course, currently has SpaceX’s Crew Dragon spacecraft to ferry its astronauts to and from the International Space Station. Crew Dragon has flown five largely flawless crewed missions since mid-2020, but with tensions high between the US and Russia, NASA would love to have a second crew transport option to reach the station. .

This means that there is great interest at NASA in Starliner’s second test. The success of this test flight would likely allow Boeing to transport the crew to the space station for the first time in early 2023.

“This is a very important step in our continued goal of having two American transport capabilities to the ISS,” said Kathy Lueders, chief of human spaceflight operations at NASA. “Robust crew services are really important to our continued commitment to our research, science and technology development that we do on the ISS, and it is essential for us to achieve our exploration goals.”

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