United Launch Alliance technicians will work this week assessing — and potentially replacing — a mechanical gas-venting valve that triggered Monday’s scrub of NASA’s historic Boeing Starliner crewed flight test at Cape Canaveral Space Force Station.

“It’s not dissimilar to many other valves like that. You have one in your home on your hot water tank that’s not all that different,” ULA President and CEO Tory Bruno said during a post-scrub NASA news conference.

“And every now and again, in rare occasions, a valve like that can get into a position where it’s just off the seat. Its temperature, its stiffness, everything is just right. And it’ll flutter. Or it’ll buzz — in this case — in cycle,” Bruno said.

Cape Canaveral: Is there a launch today? Upcoming SpaceX, NASA, ULA rocket launch schedule in Florida

NASA astronauts Suni Williams and Butch Wilmore had suited up and entered the Starliner capsule atop a ULA Atlas V rocket ahead of their 10:34 p.m. EDT Monday liftoff target. But the liquid-oxygen self-regulating solenoid relief valve— which Bruno also likened to a radiator cap on a vehicle — drew attention on the rocket’s Centaur upper stage, postponing the mission about 8:30 p.m.

Now, ULA is targeting no earlier than 9 p.m. Friday for the next launch attempt. The Atlas V will propel Wilmore and Williams on an orbital trek to the International Space Station during the first-ever crewed mission of the Starliner spacecraft.

Explaining one possible repair scenario, Bruno said ULA crews would roll the rocket off the pad back into the company’s nearby Vertical Integration Facility at Launch Complex 41; support and “stretch” the Centaur stage; replace the valve without having to remove the Starliner capsule; and roll the rocket back to the pad.

This procedure would take several days and likely push back a potential launch try to Sunday or later, Bruno said. Steve Stich, NASA’s Commercial Crew Program manager, said Boeing teams are assessing mission backup opportunities, which could push back to May 14 or 15.

“As Suni has told us a couple of times, there was nothing magical about a certain date to go launch on. So we’re taking it one step at a time. And we’re going to launch when we’re ready and fly when it’s safe to do so,” Stich said.

“Overall, things were going really well in the launch countdown. In fact, we were a little bit ahead of the timeline and talking about maybe being able to close the hatch a little bit early,” he said.

Ken Bowersox, NASA’s Space Operations Mission Directorate associate administrator, said the liquid-oxygen valve issue violated flight rules and prompted crews to begin troubleshooting.

“Good things are worth waiting for. And we’ll get a chance to see that rocket and spacecraft lift off the pad here soon,” Bowersox said.

For the latest news from Cape Canaveral Space Force Station and NASA’s Kennedy Space Center, visit floridatoday.com/space.

Rick Neale is a Space Reporter at FLORIDA TODAY. Contact Neale at Rneale@floridatoday.com. Twitter/X: @RickNeale1

Space is important to us and that’s why we’re working to bring you top coverage of the industry and Florida launches. Journalism like this takes time and resources. Please support it with a subscription here.

This article originally appeared on Florida Today: After scrub, NASA’s Boeing Starliner crewed launch Friday at earliest