Today Boeing announced another delay for the Starliner Crew Flight Test. The United Launch Alliance has fixed the faulty rocket valve that scrubbed the launch on May 6, but now Boeing has discovered a helium leak in one of Starliner’s Reaction Control System thrusters. The launch has slipped from May 17 to no earlier than May 21.

NASA astronauts Butch Wilmore and Suni Williams were getting settled in their seats on May 6 when ULA engineers detected a problem with a valve in the Atlas V rocket’s Centaur upper stage, scrubbing the launch for the day. ULA later determined the valve had to be replaced, which meant returning the rocket to the Vertical Integration Facility. ULA, Boeing and NASA set May 17 as the earliest the next attempt could be made.

At the time, NASA said Wilmore and Williams would remain in quarantine at Kennedy Space Center awaiting the next attempt, but in a hint that a longer delay might be in the offing, on May 10 the crew returned to Houston, their home base.

NASA astronauts Butch Wilmore, left, and Suni Williams, right, walk out of crew quarters at Kennedy Space Center on May 6, 2024 to head to Space Launch Complex-41 at the adjacent Cape Canaveral Space Force Station for launch on the Boeing Starliner Crew Flight Test. The launch was scrubbed that night, however. Photo Credit:(NASA/Joel Kowsky)

Indeed, today Boeing revealed that a “small helium leak” was detected in the Starliner spacecraft, so although ULA successfully replaced the Centaur’s valve, there is another delay.

#Starliner’s Crew Flight Test is now targeted to launch no earlier than 4:43 p.m. ET on Tuesday, May 21, to complete additional testing.

Learn more:

— Boeing Space (@BoeingSpace) May 14, 2024

In an update on the Starliner website, Boeing said the leak is in one of the 28 Reaction Control System (RCS) thrusters in the spacecraft’s Service Module. Those Aerojet Rocketdyne thrusters are needed to maneuver once in orbit and also would be needed if there’s a high altitude abort.

Starliner teams are working to resolve a small helium leak detected in the spacecraft’s service module traced to a flange on a single reaction control system thruster. Helium is used in spacecraft thruster systems to allow the thrusters to fire and is not combustible or toxic.

NASA and Boeing are developing spacecraft testing and operational solutions to address the issue. As a part of the testing, Boeing will bring the propulsion system up to flight pressurization just as it does prior to launch, and then allow the helium system to vent naturally to validate existing data and strengthen flight rationale. Mission teams also completed a thorough review of the data from the May 6 launch attempt and are not tracking any other issues. — Boeing

Elements of the Atlas V rocket, with its Centaur upper stage, for the Starliner Crew Flight Test. Credit: ULA

Starliner has encountered one problem after another since the first uncrewed Orbital Flight Test (OFT) in December 2019 that uncovered serious defects. Boeing decided to refly the uncrewed test before putting people on board. It was two-and-a-half years before that second flight, OFT-2, successfully took place in May 2022. Boeing and NASA were optimistic about getting this mission, the Crew Flight Test or CFT, off the ground in early 2023, but more issues emerged. Last July the launch was indefinitely delayed when Boeing discovered tape wrapped around wiring harnesses inside the spacecraft was flammable and soft link fabric sections of the parachutes were insufficiently strong.

NASA contracted with Boeing and SpaceX in 2014 to develop new crew space transportation systems to ferry astronauts to and from the International Space Station through Public-Private Partnerships where the government and the companies share development costs under a Firm Fixed Price contract. The government purchases services once the systems are certified as meeting NASA’s safety standards. The companies retain ownership and are expected to find non-NASA customers to close the business case. SpaceX’s Crew Dragon began flying astronauts in 2020 and now routinely takes both NASA and private astronauts to orbit.

Starliner is still in the test phase and because it’s a fixed price contract, Boeing has to shoulder the extra costs for the OFT reflight, schedule delays and fixing all the problems. By July 2023, Boeing had taken more than $1 billion in charges against earnings and is eager to get Starliner certified for operational missions.

ISS Program Manager Dana Weigel. Credit: NASA

They were finally ready to go this spring and the biggest challenge became finding time in the ISS schedule. Wilmore and Williams will dock with the ISS and spend just over a week there. With the constant ebb and flow of cargo resupply missions, routine 6-month crew rotations and private astronaut flights, ISS scheduling is like “the coolest game of Tetris” as cheerfully described by former ISS program manager Joel Montalbano.

Montalbano was recently promoted to Deputy Associate Administrator for the Space Operations Mission Directorate at NASA HQ. His deputy, Dana Weigel, is the new ISS program manager and has said several times that they’ve cleared the ISS schedule for the summer so Starliner can be accommodated whenever the time is right.

Hopefully that will be May 21.

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