A pair of NASA astronauts were ready to go, but a valve scrubbed their ride aboard Boeing’s CST-100 Starliner Monday night. The next shot to fly won’t be until at least May 17.
“I know everybody was excited to see a launch,” NASA’s Ken Bowersachs, associate administrator of the Space Operations Mission Directorate, said during a news conference Monday night after the scrub. We get a chance to see it thrown away.”
Butch Wilmore and Suni Williams were attached to Starliner atop a United Launch Alliance Atlas V rocket at the Cape Canaveral Space Force Station, but two hours before the scheduled liftoff, the crews abandoned the launch attempt.
ULA scrubs attempt at 1st manned Boeing Starliner mission
The cause was a technical problem with a valve inside the upper Centaur stage on the ULA rocket designed to regulate the pressure in the liquid oxygen tank.
After NASA’s astronauts had already entered the spacecraft, crews on the pad reported unexpected sounds from the rocket.
“We found that the self-regulating valve on the (liquid oxygen) side had a bit of a buzz, so it was moving in a strange behavior,” said Steve Stich, NASA Commercial Crew Program manager. “The flight rules for this flight were set ahead of time with the crew on the launch pad. Taking the scrub was the right course of action, and the United Launch Alliance team did a great job of evaluating the data and talking through various options to get us into a scrub position.
ULA President and CEO Tory Bruno said the decision to scrub was against airline rules and the real problem.
“Our philosophy is that we don’t refuel a vehicle when it’s staffed,” he said. “You can do it differently, other people can do it, but that’s our philosophy. So we built our flight rules around that.
He noted that it’s a problem they’ve seen before on ULA rockets, and that if humans aren’t on board, it’s a simple fix on the spot.
“It’s no different with a lot of valves like this, you have one in your hot water tank at home, it’s no different,” he said. “Every now and then on rare occasions, a valve like that can get to the point where it’s out of seat. Its temperature, its stiffness, everything’s just right, it’ll flutter or, in this case, ring in the cycle.
He said that forcing the valve to rotate is fine.
“Once we got the crew out, we cycled the valve and it stopped beeping,” he said. “If it’s a satellite, that’s our standard procedure, and the satellite will already be in orbit.”
But with humans on board, ULA’s rules did not change the fuel status of volatile cryogenic propellants.
“I promised Butch and Suni a boring evening,” Bruno said. “I don’t think it should be too boring. But we’re going to follow our rules and we’re going to make sure the crew is safe.
But another problem is related to valve life. Bruno said it was qualified to open and close 200,000 times at full pressure. Based on Monday night’s data, flutter on the valve is possible, and in fact, if it were to fully open and close, it would be close to that 200,000 limit.
Bruno said the pressure applied by ULA is verifying that it is not at full capacity, meaning only a partial debit is possible against the 200,000 limit. Bruno said there are no instruments that actually measure the valve, and data must be found from surrounding hardware.
After looking at data overnight and throughout the day Tuesday, NASA said the decision was made to replace the valve, which meant rolling the rocket back to Boeing’s Vertical Integration Facility.
The new target launch date is Friday, May 17, at 6:16 p.m. Wednesday, so the rocket can be “stretched” to access the valve, but the Starliner can remain atop the rocket without being removed.
“We have spare valves. We know how to do it. We’ve done it before, but it takes days,” Bruno said.
The good news for NASA is that the normally busy ISS has had some time without new cargo or crew missions.
“We’re in no rush to fly from a station standpoint,” said NASA ISS Manager Dana Weigel. Our next docking vehicle is coming out in August, so there will be plenty of time.
When Starliner launches, it will mark the final qualification flight required for the spacecraft to be used for routine missions for ISS sharing duties with SpaceX’s Crew Dragon.
Wilmore and Williams will test the spacecraft’s manual functions before its eight-day stay at the ISS. They will then take off and test more manual operations on the return trip by landing in the desert in the western United States.
“I talked to the crew before we got here, and they’re in good spirits,” said Mark Nappi, project manager for Boeing’s commercial group. “They fully understand these types of situations. A lot of things have to go right. And it’s not most things, everything has to go right before we start.
If all goes well, Boeing could fly its first regular mission, Starliner-1, in February 2025, the first of six contracted flights to the ISS that will fly once a year until 2030. Station.
“Today was a good dry run for the whole process,” Nappi said. “Let’s wait and see what the problem is. Let’s set the next release date. We’ll start the clock again. Hope to see you back here in a couple of days.
