ULA crews targeting May 17 or later for NASA's next Boeing Starliner crewed launch attempt

United Launch Alliance technicians will work this week replacing a pressure regulation valve on a liquid oxygen tank that triggered Monday's scrub of NASA's historic Boeing Starliner crewed flight test at Cape Canaveral Space Force Station.

Now, ULA is targeting no earlier than 6:16 p.m. May 17 for the next launch attempt. The Atlas V will propel NASA astronauts Suni Williams and Butch Wilmore on an orbital trek to the International Space Station during the first-ever crewed mission of the Starliner spacecraft.

"ULA plans to roll the rocket, with Boeing’s Starliner spacecraft, back to its Vertical Integration Facility 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," company officials announced Tuesday night.

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Williams and 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 ULA President and CEO Tory Bruno 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.

"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," Bruno said during a post-scrub late-night 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," he said.

Explaining a 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.

"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," said Steve Stich, NASA’s Commercial Crew Program manager.

"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," Stich 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.

In its Tuesday night statement, ULA officials said, "NASA astronauts Butch Wilmore and Suni Williams will remain at crew quarters in health stabilization until the next launch opportunity."

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 [email protected]. Twitter/X: @RickNeale1

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This article originally appeared on Florida Today: After scrub, NASA's Starliner crewed launch set for May 17 at earliest