Boeing will try again to launch astronauts on its spaceship this weekend

Boeing is gearing up for yet another attempt to launch NASA astronauts onboard its Starliner spacecraft.

It’s a key test flight — the first time a crew will fly the vehicle to the International Space Station.

The launch was originally scheduled for May 6, but that attempt was called off with roughly two hours left in the countdown. Now, liftoff is expected at 12:25 p.m. ET Saturday from Cape Canaveral Space Force Station, Florida. The spacecraft will ride into orbit atop an Atlas V rocket built by United Launch Alliance, a joint venture of Boeing and Lockheed Martin.

The test flight is intended to show that the Starliner can safely carry astronauts to and from the space station. If it is successful, NASA can authorize Boeing to conduct routine trips to the orbiting outpost, which would give it a long-awaited second option to SpaceX’s Crew Dragon capsule.

Boeing’s May 6 launch was canceled because of an issue with a valve on the Atlas V rocket. NASA astronauts Barry “Butch” Wilmore and Sunita Williams were already seated and strapped into the capsule when mission controllers opted to stand down.

While work to fix the booster’s malfunctioning valve was underway, a separate problem — this time, a helium leak — was found in the Starliner capsule’s propulsion system, according to NASA. The discovery forced additional delays to a project that already has faced years of setbacks and budget overruns.

At a news briefing last week, mission controllers said the rocket’s valve was successfully replaced but added that the helium leak would not be repaired before the coming flight.

Steve Stich, manager of NASA’s Commercial Crew Program, said that the slow leak was extensively analyzed and that it was determined that it is unlikely to pose a threat to the crew, the mission or the spacecraft.

Repairing the leak would require a much longer delay because the spacecraft would need to be detached from the rocket, said Mark Nappi, Boeing’s vice president for the commercial crew program.

Stich called the issue a “design vulnerability,” because in the unlikely event that a number of systems were to fail while the helium leak persisted, it could leave the Starliner capsule without enough working thrusters to perform crucial maneuvers, including de-orbit burns to help the astronauts return to Earth.

In the end, however, mission managers said they felt comfortable proceeding with Saturday’s test flight.

“We could handle this particular leak if that leak rate were to grow even up to 100 times,” Stich said.

Representatives from NASA, Boeing and United Launch Alliance met Wednesday for a readiness review and officially voted to continue with Saturday’s launch preparations.

Wilmore and Williams, who quarantined in Houston while engineers worked on the rocket and the spacecraft, arrived back at NASA’s Kennedy Space Center in Florida on Tuesday.

If all goes according to plan, they will spend about a week at the International Space Station before they return to Earth and touch down at the Starliner’s primary landing site at New Mexico’s White Sands Missile Range.

Boeing hopes to challenge the dominance of Elon Musk’s SpaceX, which has been carrying NASA astronauts to and from the space station since 2020. Both companies developed their spacecraft as part of the Commercial Crew Program, which NASA established after its space shuttle fleet retired, to provide incentives and help pay for creating commercially built vehicles able to reach low-Earth orbit.

However, the Starliner program has experienced many bumps along the way.

In 2019, the capsule’s uncrewed debut flight was cut short after software glitches prevented it from attempting to dock at the space station. Subsequent fuel valve issues caused several delays before Boeing was able to demonstrate in 2022 that the Starliner could dock at the ISS and return to Earth.

The company as a whole has also faced heightened scrutiny after a panel blew out midflight on one of its 737 Max 9 airplanes.