NASA Update on Starliner Engine Problems: That’s Good

Before Boeing’s Starliner crew capsule is allowed to depart the International Space Station and head home, NASA managers want to make sure the spacecraft’s troubled control engines can help guide the two-person crew home.

The astronauts, who launched June 5 on the first crewed test flight of the Starliner spacecraft, agreed with managers, though they said Wednesday they were comfortable returning the capsule to Earth in the event of an emergency that might require evacuating the space station.

Five of the Starliner’s 28 reaction control system thrusters shut down as the spacecraft approached the space station last month. Starliner’s flight software disabled the five control thrusters when they began to overheat and lose thrust. Four of the thrusters were later restored, though some were unable to reach full power levels when Starliner arrived for docking. In mid-June, Starliner astronauts fired the thrusters again, with thrust levels closer to normal.

“What we want to know is that the thrusters are capable of working; if their thrust ratio, whatever it is, we can put them in a package that will provide us with a deorbit burn,” said Suni Williams, a NASA astronaut who serves as Starliner pilot. “That’s the main purpose we need.” [for] Service Module: To give us a good burn to get us out of orbit so we can get back.

These small engines aren’t necessary for the in-orbit fire, which will use a different set of engines to slow Starliner down enough to deorbit and head for landing. But Starliner does need enough thrusters to maneuver in the right direction for the in-orbit fire.

The test flight marks the first time astronauts have flown into space on Boeing’s Starliner, after years of delays and setbacks. Starliner is NASA’s second commercial crew capsule, and is poised to join SpaceX’s Crew Dragon on a series of missions that will carry astronauts to and from the space station over the rest of the decade.

But first, Boeing and NASA need to safely complete the Starliner test flight and resolve the spacecraft’s propellant issues and helium leaks before moving forward with operational crew rotations. The Crew Dragon spacecraft is currently docked at the station, but Steve Stich, NASA’s Commercial Crew Program manager, told reporters Wednesday that for now, Williams and Starliner commander Butch Wilmore are planning to return home aboard the Starliner.

“The nice thing about the Commercial Crew Program is that we have two different vehicles and two different systems that we can use to get the crew back,” Stitch said. “So we have more time to review the data and then decide if we need to do anything different. But the main option today is to get Butch and Sonny back on Starliner. Right now, we don’t see any reason why that wouldn’t happen.”

Mark Nappi, Boeing’s Starliner program manager, said officials have identified more than 30 actions to investigate five “small” helium leaks and problems with the Starliner’s service module thrusters. “All of those items are scheduled to be completed by the end of next week,” Nappi said.

“It’s a test flight, our first with crew, and we’re putting in a little extra effort to make sure we understand everything before we commit to going out of orbit,” Stitch said.