NASA finds more problems with Boeing’s Starliner, but crew launch is scheduled for June 1

Enlarge / Boeing’s Starliner spacecraft atop its Atlas V rocket on the launch pad earlier this month.

Top officials at NASA and Boeing told reporters Friday that they plan to launch the first crewed test flight of the Starliner spacecraft on June 1, following several weeks of detailed analysis of a helium leak and a “design vulnerability.” “in the propulsion of the ship. system.

Extensive data reviews over the past two and a half weeks determined a probable cause of the breach, which officials described as small and stable. During these reviews, engineers also built confidence that even if the leak worsened, it would not add any unacceptable risk to the Starliner test flight to the International Space Station, officials said.

But engineers also discovered that an unlikely mix of technical failures in Starliner’s propulsion system (accounting for 0.77 percent of all possible failure modes, according to Boeing’s program manager) could prevent the spacecraft from Perform a deorbit at the end of the mission.

“While we were studying the helium leak, we also looked at the rest of the propulsion system, just to make sure we didn’t have other things to worry about,” said Steve Stich, NASA’s commercial crew program manager. that he awarded a $4.2 billion contract to Boeing in 2014 for the development of the Starliner spacecraft.

“We found a design vulnerability… in the prop [propulsion] as we were looking at this particular helium leak, where for certain failure cases that are very remote, we did not have the ability to run deorbitation burn with redundancy,” Stich said at a news conference Friday.

These two problems, discovered one after the other, have kept the Starliner test flight grounded to give engineers time to find solutions. This is the first time astronauts will fly to orbit in a Starliner spacecraft, following two unmanned demonstration missions in 2019 and 2022.

The Starliner program is years behind schedule, primarily due to problems with the spacecraft’s software, parachutes and propulsion system, supplied by Aerojet Rocketdyne. Software problems disrupted Starliner’s first test flight in 2019 before it could dock at the International Space Station, and forced Boeing to conduct an unplanned second test flight to gain confidence that the spacecraft is safe enough. for astronauts. NASA and Boeing delayed the second pilotless test flight nearly a year to overcome a problem with corroded valves in the ship’s propulsion system.

Last year, just a couple of months before its launch on the crewed test flight, officials discovered a design problem with Starliner’s parachutes and discovered that Boeing installed flammable tape inside the capsule’s cabin. Boeing’s ill-fated Starliner finally appeared ready to fly on the long-delayed crewed test flight from Cape Canaveral Space Force Station, Florida.

NASA Commander Butch Wilmore and pilot Suni Williams were strapped into their seats inside Starliner on May 6 when officials stopped the countdown due to a faulty valve on NASA’s United Launch Alliance Atlas V rocket. spacecraft. ULA returned the rocket to its hangar to replace the valve, with an eye toward another launch attempt in mid-May.

But ground crews detected the helium leak in the Starliner service module after the countdown. After ironing out some initial issues, the leak rate increased to about 70 psi per minute. Since then, the leak rate has stabilized.

“That gave us pause as the leak rate grew and we wanted to understand what was causing that leak,” Stich said.

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