Continued helium leak causes additional delay for Boeing’s ill-fated Starliner spacecraft

The launch of Boeing already delayed Starliner spacecraft will be postponed for at least four more days, from next Tuesday to May 25, as work is underway to address concerns about a small helium leak in the capsule’s propulsion system, officials said Friday.

Mission commander Barry “Butch” Wilmore and co-pilot Sunita Williams now plan to launch from Pad 41 at the Cape Canaveral Space Force Station in Florida for a week starting Saturday at 3:09 p.m. EDT and set up a docking station at the International Space Station next Saturday. May 26, at 4:12 p.m

The astronauts had hoped to launch the Starliner’s first manned test flight on May 6, but the countdown is on was cancelled due to problems with an oxygen relief valve in the Centaur upper stage of their Atlas 5 rocket.

The United Launch Alliance-built Atlas 5 was transported from the launch site back to the company’s nearby Vertical Integration Facility, where the suspect valve was replaced and cleared for launch.

The unrelated helium leak in the Starliner’s fuel pressure system was detected during the original countdown to takeoff but remained within safe limits for the flight. After the Atlas 5 and Starliner were reset to the VIF to replace the oxygen valve, managers decided to take a closer look at the helium problem.

The leak was discovered in the piping of the No. 2 helium manifold in one of four “doghouse” assemblies located on the outside of the Starliner’s drum-shaped service module. Each kennel has four OMAC (Orbital Maneuvering and Attitude Control) engines and four small maneuvering thrusters with a reaction control system.

Pressurized helium gas is used to deliver propellants to the rocket motors in each doghouse, as well as four powerful launch abort engines that would only be fired in the event of a catastrophic problem with the Atlas 5 en route to orbit.

Engineers tightened the bolts on a flange where the leak was found, pressurized the pipes and then ran tests to see if the leak was still present. In the meantime, the launch has been postponed to May 21st.

But as it turned out, tests showed the leak was still there. Mission managers considered a number of options to address the problem, but decided Friday to work toward a May 25 launch date pending further data review and analysis to show that the leak, which is currently stable and within acceptable limits, is present lies, will not worsen in flight.

“Pressure testing … demonstrated that the leak in the flange is stable and would not pose a risk during flight at this level,” NASA said in a blog post. “The tests also showed that the remainder of the engine system is effectively sealed throughout the service module.

“Boeing teams are working to develop operational procedures to ensure the system maintains sufficient performance and appropriate redundancy during flight. As this work progresses, (mission managers) will need the next few days to review the data and procedures to make a final decision before proceeding with the flight countdown.

Wilmore and Williams, both experienced Navy test pilots and astronauts with a total of four flights to the station, flew back to the Johnson Space Center in Houston after scrubbing on May 6 to participate in additional flight simulations. They are expected to return to Florida next week.

The Starliner is one of two commercially developed crew ferry ships ordered by NASA after the shuttle program was canceled in 2011. SpaceX received a contract worth $2.6 billion for development the company’s Crew Dragon spacecraft and Boeing received $4.2 billion to develop the Starliner.

NASA needed spacecraft from a variety of manufacturers to ensure that the agency still had a way to get astronauts to the space station even if a problem grounded a company’s ferry ship.

SpaceX launched its first two-man crew in 2020. Since then, the company has launched eight NASA-sponsored crew rotation flights to the station, three commercial research missions to the laboratory and a privately funded trip with two men and two women to low Earth orbit. A total of 50 people flew into space aboard Crew Dragons.

Wilmore and Williams will be the first astronauts to fly aboard a Starliner after a series of technical glitches, including serious software problems during a first unmanned test flight in December 2019 and corroded propulsion system valves affecting a second unmanned test mission in May 2022 delayed.

Engineers encountered questions about parachute harness connectors and protective tape wrapped around wiring, which posed a fire hazard if a short circuit occurred. Work to fix these and other issues delayed the first pilot launch until this month.