United Launch Alliance (ULA) called off the much-anticipated crewed test flight of Boeing's Starliner just hours before the scheduled liftoff due to a valve issue on the rocket's Centaur upper stage. The malfunctioning valve caused a scrub, leading to a delay until at least Friday, May 10, for the next launch attempt.
A Smooth Countdown and Crew Egress
The countdown for the Starliner Crewed Flight Test was running without trouble, with the crew already in their flight suits and on their way to Space Launch Complex 41 (SLC-41) aboard Boeing's "AstroVan." Once at the pad, the Boeing and ULA teams secured the crew into the Starliner capsule, sealing the hatch in preparation for the launch. At this point, everything seemed to be running smoothly, with the teams ahead of schedule for the crew ingress.
ULA's Atlas V Valve Issue Leads to Scrub
However, about two hours before the planned launch, ULA controllers noticed "fluttering" in a pressure relief valve on the Centaur upper stage. Tory Bruno, CEO of ULA, mentioned that while this was a known issue from previous Atlas launches, resolving it would require changing the rocket's fueling state, which isn't allowable while the crew is at the pad. As a result, the launch had to be scrubbed for safety reasons.
Although ULA has addressed similar valve issues in the past by forcing the valve shut and returning it to normal operations, the situation this time required careful inspection to ensure the valve hadn't exceeded its operational lifespan. The estimated lifespan is about 200,000 cycles, and there's no remote sensor to determine if this limit had been reached.
Troubleshooting and a New Launch Date
To address the problem, ULA teams began a thorough inspection of the valve, working overnight and into the next day to assess whether a replacement was necessary. If so, the Centaur upper stage would need to be decompressed, requiring a return to the Vertical Integration Facility. Fortunately, this process wouldn't require the disassembling of Starliner from the rocket, but it would add a few days to the launch timeline.
With the valve issue under investigation, ULA announced a new launch date of no earlier than Friday, May 10. The exact timeline for the fix is unclear, and there's no confirmation yet on whether the valve will be replaced or if other steps will be taken to resolve the issue. However, once the rocket is cleared for launch, the mission can proceed as planned.
While delays are always disappointing, safety remains the top priority for crewed launches. Stay tuned for more updates on this developing story as we get closer to the revised launch date.
