The CST-100 Starliner capsule lifted off shortly before 7 p.m. EDT (2300 GMT) from the Cape Canaveral Space Station in Florida, aboard an Atlas 5 rocket from United Launch Alliance, a joint venture of Boeing and Lockheed Martin.
According to plans, the capsule will reach the space station within about 24 hours and dock with the research center, which orbits about 250 miles (400 kilometers) above Earth on Friday evening.
The Boeing spacecraft is scheduled to spend four to five days attached to the space station before detaching and returning to Earth, landing with parachute and airbag protection in the White Sands desert in New Mexico.
Mission success would take Starliner a major step toward providing NASA with a second, reliable means of transporting astronauts to and from the station.
Since the resumption of manned flights to orbit from American soil in 2020, nine years after the end of the space shuttle program, NASA has had to rely on transporting astronauts on Falcon 9 rockets and Crew Dragon capsules from billionaire Elon Musk’s SpaceX company.
Previously, the only other option for access to the orbiting laboratory was the Russian Soyuz spacecraft.
“Having a backup is important to the country,” NASA chief Bill Nelson told Reuters hours before the launch.
The launch also comes at a critical time for Boeing, as the Chicago-based company struggles to emerge from successive crises in its aircraft business and its space defense unit. The Starliner program alone has forced Boeing to incur $595 million in costs since the failure of its first unmanned test flight into orbit in 2019.
The launch was a repeat of a test mission in 2019 that failed to deliver the capsule to the space station due to a malfunction in the flight program. Subsequent problems with the Starliner’s propulsion system, supplied by Aerojet Rocket Dine, led to Boeing canceling the capsule launch attempt last summer.
The spacecraft remained idle for another nine months while the two companies wrangling over the cause of the problem and which company was responsible for fixing it, Reuters reported last week.
Starliner was developed under a $4.5 billion contract from NASA to provide the US space agency with a second means of reaching low Earth orbit, alongside SpaceX.
If the second unmanned flight into orbit is successful, Starliner could blast off its first team of astronauts in the fall, although NASA officials caution that the timeframe may be pushed back.