Boeing is preparing for another attempt to launch NASA astronauts on its Starliner spacecraft.
It’s a key test flight — the first time a crew will fly a vehicle to the International Space Station.
The launch was originally scheduled for May 6, but that attempt was canceled with about two hours left in the countdown. It is now expected to lift off on Saturday at 12:25 PM ET from Cape Canaveral Space Force Station, Florida. The spacecraft will fly into orbit atop an Atlas V rocket built by United Launch Alliance, a joint venture between Boeing and Lockheed Martin.
The test flight aims to demonstrate that the Starliner can safely transport astronauts to and from the space station. If successful, NASA may authorize Boeing to make routine trips to the orbital outpost, giving it a long-awaited second option after SpaceX’s Crew Dragon capsule.
Boeing’s May 6 launch was canceled due to a valve problem on the Atlas V rocket. NASA astronauts Barry “Butch” Wilmore and Sunita Williams were already seated and strapped in the capsule when mission controllers decided to back off.
While work to fix the faulty booster valve was underway, according to NASA, a particular problem — this time, a helium leak — was found in the Starliner capsule’s propulsion system. The revelation led to further delays to a project that was already facing years of delays and budget overruns.
At a news conference last week, mission controllers said the rocket’s valve had been successfully replaced, but added that the helium leak would not be repaired before the upcoming flight.
Steve Stich, manager of NASA’s Commercial Crew Program, said the slow leak was extensively analyzed and determined to be 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 have to be separated from the rocket, said Mark Nappi, Boeing’s vice president for the commercial crew program.
Stich called the problem a “design vulnerability,” because in the unlikely event that numerous systems fail while the helium leak continues, the Starliner capsule could be left without enough working thrusters to perform key maneuvers, including de-orbital burnouts to help the astronauts return to Earth.
Ultimately, however, mission leaders said they felt comfortable continuing with Saturday’s test flight.
“We could deal with this particular leak if that leak rate went up to even 100 times,” Stich said.
Representatives from NASA, Boeing and the United Launch Alliance met Wednesday to review readiness and officially voted to continue preparations for Saturday’s launch.
Wilmore and Williams, who were quarantined in Houston while engineers worked on the rocket and spacecraft, returned to NASA’s Kennedy Space Center in Florida on Tuesday.
If all goes according to plan, they will spend about a week on the International Space Station before returning to Earth and landing at the main Starliner landing site at White Sands Missile Range in New Mexico.
Boeing hopes to challenge the dominance of Elon Musk’s SpaceX, which has been ferrying 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 the creation of commercially built vehicles that can reach low Earth orbit.
However, the Starliner program experienced many problems along the way.
In 2019, the unmanned capsule’s maiden flight was aborted after software problems prevented its attempt to dock with the space station. Subsequent problems with the fuel valve caused several delays before Boeing was able to demonstrate in 2022 that the Starliner could dock with the ISS and return to Earth.
The company as a whole has also faced heightened scrutiny after a panel blew up mid-flight on one of its 737 Max 9 planes.