Faulty Atlas V Valve Leads to Rescheduling of NASA’s Boeing Starliner Crew Flight Test

A United Launch Alliance Atlas V rocket with Boeing’s CST-100 Starliner spacecraft aboard is seen on the launch pad illuminated by spotlights at Space Launch Complex 41 at Cape Canaveral Space Force Station in Florida. The picture was taken on Test, Sunday, May 5, 2024, ahead of NASA’s Boeing Crew Flight. Credit: NASA/Joel Kowsky

NASA’s Boeing Crew Flight Test to the International Space Station has been postponed to no earlier than May 17 due to a faulty valve in the Atlas V rocket’s upper stage. The United Launch Alliance will replace the valve after discovering issues during prelaunch checks. Astronauts Butch Wilmore and Suni Williams remain in quarantine at NASA Kennedy, awaiting the next launch opportunity.

NASA’s Boeing Crew Flight Test now is targeted to launch no earlier than 6:16 p.m. EDT Friday, May 17, to the International Space Station. Following a thorough data review completed on Tuesday, ULA (United Launch Alliance) decided to replace a pressure regulation valve on the liquid oxygen tank on the Atlas V rocket’s Centaur upper stage.

ULA plans to roll the rocket, with Boeing’s Starliner spacecraft, back to its Vertical Integration Facility at Cape Canaveral Space Force Station in Florida on Wednesday, May 8, to begin the replacement. The ULA team will perform leak checks and functional checkouts in support of the next launch attempt.

The oscillating behavior of the valve during prelaunch operations, ultimately resulted in mission teams calling a launch scrub on May 6. After the ground crews and astronauts Butch Wilmore and Suni Williams safely exited from Space Launch Complex-41, the ULA team successfully commanded the valve closed and the oscillations were temporarily dampened. The oscillations then re-occurred twice during fuel removal operations. After evaluating the valve history, data signatures from the launch attempt, and assessing the risks relative to continued use, the ULA team determined the valve exceeded its qualification and mission managers agreed to remove and replace the valve.

NASA, Boeing, and United Launch Alliance officials discussed details of a scrub decision made ahead of the first launch attempt for NASA’s Boeing Crew Flight Test. Participants in the briefing included Ken Bowersox, associate administrator, NASA’s Space Operations Mission Directorate; Steve Stich, manager, NASA’s Commercial Crew Program; Tory Bruno, president and CEO, United Launch Alliance; Dana Weigel, manager, NASA’s International Space Station Program and Mark Nappi, vice president and program manager, Boeing’s Commercial Crew Program. Credit: NASA/Chris Chamberland

Mission managers discussed the details leading to the decision to scrub the May 6 launch opportunity during a news conference (see video above) shortly after the scrub call at NASA’s Kennedy Space Center in Florida.

Wilmore and Williams will remain in crew quarters at NASA Kennedy in quarantine until the next launch opportunity. The duo will be the first to launch aboard Starliner to the space station as part of the agency’s Commercial Crew Program.