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After weeks of troubleshooting and recent testing aimed at replicating the problems plaguing Boeing’s Starliner spacecraft, NASA and Boeing officials are not yet ready to set a return date for the two astronauts piloting the vehicle in their inaugural manned test flight.
Engineers finally have some possible answers about what caused some of the Starliner’s problems during the first leg of its journey, which included helium leaks and thrusters that stopped working unexpectedly.
The revelations come after Boeing and NASA spent the past few weeks working to understand the problem on the ground.
At a site in New Mexico, engineers fired test engines more than 1,000 times, replicating how the space-bound Starliner’s thrusters would have fired. They then fired up the thruster to test various ways the engines could fire on the way home from space, according to Boeing.
The purpose of this test was to gain a better understanding of why the spacecraft’s thrusters shut down unexpectedly and what dangers – if any – are associated with restarting these thrusters.
Officials said they were able to replicate how propellants in space deteriorated during flight with ground tests. And the tests may have helped give engineers a better understanding of the “root cause” of the problem: Increased heat inside the thrusters may be causing the Teflon seals to swell, restricting propellant flow.
These tests “gave us additional confidence to undock in return,” said Mark Nappi, manager of Boeing’s Commercial Crew Program.
Still, officials did not say definitively Thursday that the Starliner spacecraft that carried veteran NASA astronauts Butch Wilmore and Suni Williams to the International Space Station would be the same vehicle that brought the astronauts home.
“There are many good reasons to complete this mission and bring Butch and Suni home on the Starliner,” Stich said after noting that NASA has contingency options if the Starliner is not approved to bring astronauts home.
“We need to go through the process properly,” he added. “We have another critical Starliner mission management team to review all the data from the thrusters we just talked about.”
“Of course I’m very confident that we have a good vehicle to bring the crew back,” Nappi said.
As of Thursday, astronauts have been in space for about 50 days. NASA has previously indicated that the Starliner can remain in space for a maximum of 90 days.
Additional Starliner Tests
Separately, engineers may have made progress in understanding the helium leaks that hampered the first leg of Starliner’s journey. But Boeing and NASA will look at that issue again during additional testing of the vehicle that continues this weekend, Stich said.
“The key attributes of the flight logic are really that we understand helium leaks – we understand the stability of the leaks and how we can manage them if they increase,” Stich said.
This test will include firing 27 Starliner thrusters while the vehicle remains docked to the ISS in space.
NASA and Boeing also plan to conduct a review to plan the undocking of the Starliner, which “could occur as early as the end of next week,” according to NASA Commercial Crew Program Manager Steve Stich.
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