What's behind latest delay of Boeing Starliner launch from Florida?

After making it to the launch pad earlier this month only to face an issue with the Atlas V rocket, this week's planned launch of Boeing’s Starliner from Cape Canaveral is delayed yet again − now the inaugural crewed flight is set for no earlier than Tuesday, May 21st.

Originally set for May 6, the launch was scrubbed when a faulty oxygen valve on the Atlas V was discovered with almost two hours left until launch. The crew was in the process of getting in the spacecraft when teams called off the launch to investigate the valve.

United Launch Alliance teams decided to replace the valve and to do so required rolling the rocket and the attached Starliner back to the Vertical Integration Facility.

With the valve replaced May 11, the plan was to push ahead toward a launch this Friday, but now another issue has cropped up: this time on the spacecraft itself.

Latest delay on Starliner due helium leak on Starliner

A statement released by Boeing said that a small helium leak was detected in the spacecraft’s service module — the disposable module which sits below the spacecraft and contains the thrusters and launch abort engines.

The helium leak was found to be coming from a "flange on a single reaction control system thruster." While helium is not reactive, it is used within thrusters to assist in firing. In order to ensure the safety of the spacecraft, the Boeing team states they plan to fully investigate the leak and that means bringing Starliner’s propulsion system to the state seen before launch.

Boeing added that they aren't currently tracking any other issues with the spacecraft.

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Rocket valve caused initial delay

The initial delay was prompted by an issue with an oxygen valve on the Atlas V rocket.

"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," ULA President Tory Bruno said during a press conference which followed the May 6 night scrub.

"We've seen that before," said Bruno. "What you would typically do is activate the solenoid that forces the valve closed − cycling the valve, if you will − then you turn that on and let it return.”

A United Launch Alliance Atlas V rocket and Boeing Starliner capsule remain on the launch pad Tuesday, May, 7, 2024. Launch to the International Space Station was postponed due to a problem with a liquid oxygen valve on the second stage. Craig Bailey/FLORIDA TODAY via USA TODAY NETWORK
A United Launch Alliance Atlas V rocket and Boeing Starliner capsule remain on the launch pad Tuesday, May, 7, 2024. Launch to the International Space Station was postponed due to a problem with a liquid oxygen valve on the second stage. Craig Bailey/FLORIDA TODAY via USA TODAY NETWORK

But with a crew involved, the launch had to be stopped for the day. The astronauts were never in any danger, officials noted.

The next day ULA crews investigated the valve issue, only to make the call later in the day to replace it.

New Starliner launch date

The launch of Starliner is now set for no earlier than 4:43 p.m. Tuesday, May 21 at 4:43 p.m. The astronauts, Butch Wilmore and Suni Williams, reportedly returned to Houston to be with their families and now plan to return to Florida in the coming days.

The FLORIDA TODAY Space Team will continue to bring you the latest information on this story and all the launches at the Cape at Floridatoday.com/space.

Brooke Edwards is a Space Reporter for Florida Today. Contact her at bedwards@floridatoday.com or on X: @brookeofstars.

This article originally appeared on Florida Today: Delayed again: Boeing Starliner crewed launch pushed back to next week