NASA extends Starliner stay at space station to further assess helium leaks and thruster issues

Boeing’s leak-prone Starliner capsule will remain docked with the International Space Station for four more days, NASA announced Tuesday, returning to Earth with a pre-dawn landing in White Sands, New Mexico, on June 26 to end an extended 20-day test flight – the first with astronauts on board.

The additional docked time will give Starliner commander Barry “Butch” Wilmore and co-pilot Sunita Williams more time to help aboard the station as flight controllers continue to examine telemetry and finalize reentry plans with five known helium leaks. in the capsule’s propulsion system. and unexpected behavior in multiple jet maneuvers.

One jet will not be used for the remainder of the flight, but the other suspected boosters were successfully “hot fired” during a test on Saturday, giving managers confidence they will work as needed to get the Starliner out of orbit for reentry and landing. . .

As for helium leaks, engineers say the spacecraft has more than seven times the amount needed for the remainder of the flight. During Saturday’s hot fire test, leak rates were lower than indicated by telemetry at the start of the mission, but engineers are still evaluating the data to better understand the system’s behavior.

“We learned that our helium system is not working as designed. While manageable, it is still not performing as we designed,” said Mark Nappi, Boeing’s Starliner program manager. “So we have to figure it out.”

As for thrusters, “there are some things about our flight profile and/or our parameters… where our thrusters are not working (as expected). So we have to figure that out.” But he said Boeing intends to “completely eliminate” both problems, which he described as “annoying,” before the Starliner flies again.

“The good thing about the situation is that we can stay on the ISS a little longer and get as much data as possible so that we can fully understand this as best we can.”

Meanwhile, Steve Stich, manager of NASA’s Commercial Crew Program, said the Starliner could safely transport Wilmore and Williams back to Earth should a problem arise that requires an immediate departure.

But as it currently stands, Wilmore and Williams will undock from the space station’s forward port at 10:10 p.m. EDT on June 25 and fire the spacecraft’s aft-facing thrusters to deorbit early the next day, setting up a para- crashes – and – airbag-assisted landing at White Sands at 4:51 a.m. EDT.

The day before Wilmore and Williams depart, ISS astronauts Tracy Dyson and Mike Barratt plan to venture outside the station for a spacewalk, or EVA, to retrieve a faulty radio transmitter and collect swabs near the air vents and the station’s decompression chamber to find out if there are any microorganisms. managed to get out and survive in the hostile environment of space.

During an initial attempt on June 13, in what was supposed to be the first of three planned spacewalks, Dyson and Matthew Dominick, his original partner, never left the airlock. Dominick reported a “discomfort issue” with the spacesuit and the EVA was cancelled.

Rather than waste time investigating and correcting the problem with Dominick’s suit, and given the amount of oxygen available in the airlock, NASA managers decided to retry the original spacewalk with Dyson and Barratt and combine the tasks planned for the second and third departures in a single tour on July 2nd.

But the spacewalk’s timeline depends on Starliner’s undocking, which is the top priority in the near term.

Already four years late, the Starliner was released on June 5tha month later than planned due to problems with its Atlas 5 rocket, problems with a countdown computer and an initial helium leak in the system used to pressurize the capsule’s thrusters.

NASA and Boeing managers decided the leak was too small to pose a safety threat and the ship was cleared for launch. Once in orbit and on the way to the space station, however, four more helium leaks developed and the Starliner’s flight computer shut down seven maneuvering jets when telemetry did not meet pre-launch expectations.

Stich said Saturday’s hot-fire test showed that the jets needed for post-dedocking maneuvers and the critical deorbit “burn” will function as needed to lift the spacecraft out of orbit for reentry. Likewise, he said engineers are confident that the helium leaks can be managed even if one or more worsen after undocking.

But the additional days docked at the space station will give engineers more time to review data and monitor telemetry from Starliner’s service module, where the thrusters and helium pressurization plumbing are located. Engineers will not be able to study the actual hardware because the service module will be jettisoned before reentry and burn up in the atmosphere.

“We are taking longer, given that this is a crewed vehicle, we want to make sure we leave no stone unturned,” Stich said. “We also want to look at the systems and the potential interaction between the systems and make sure we didn’t miss anything before we come back.”

“I like the fact that the vehicle stays a little longer,” he added. “I like the fact that we are looking at the thermal performance of the vehicle, how the space station charges the batteries. We’re seeing these types of cycles, which are absolutely necessary for subsequent missions. There’s a silver lining to staying a little (longer on the space station).”

Before launch, NASA managers hoped the Starliner test flight would pave the way for the spacecraft’s certification for operational space station crew rotation missions starting early next year. But given the problems encountered at the beginning of the flight, certification may be delayed depending on what is necessary to resolve the problems identified so far.