Boeing launched astronauts for the first time on Wednesday, belatedly joining SpaceX as a second taxi service for NASA.

A pair of NASA test pilots blasted off aboard Boeing's Starliner capsule for the International Space Station, the first to fly the new spacecraft.

The trip by Butch Wilmore and Suni Williams was expected to take 25 hours, with arrival on Thursday. They will spend just over a week at the orbiting lab before climbing back into Starliner for a remote desert touchdown in the western U.S. on June 14.

"Let's get going!" Wilmore called out a few minutes before liftoff.

Half an hour later, he and Williams were safely in orbit and on their way to the space station. Back at Cape Canaveral, the relieved launch controllers stood and applauded. After all the trouble leading up to Wednesday's launch, including two scrapped countdowns, everything went smoothly before and during liftoff, prompting congratulations from SpaceX's Elon Musk and others.

"Today it all lined up," said Boeing program manager Mark Nappi.

Years late because of spacecraft flaws, Starliner's crew debut comes as the company struggles with unrelated safety issues on its airplane side.

Wilmore and Williams – retired Navy captains and former space station residents – stressed repeatedly before the launch that they had full confidence in Boeing's ability to get it right with this test flight.

Crippled by bad software, Starliner's initial test flight in 2019 without a crew had to be repeated before NASA would let its astronauts strap in. The 2022 do-over went much better, but parachute problems later cropped up and flammable tape had to be removed from the capsule.

Wednesday's launch was the third attempt with astronauts since early May, coming after a pair of rocket-related problems, most recently last weekend. A small helium leak in the spacecraft's propulsion system also caused delays, but remained extremely low and manageable.

Boeing was hired alongside SpaceX a decade ago to ferry NASA's astronauts to and from the space station. The space agency wanted two competing U.S. companies for the job in the wake of the space shuttles' retirement, paying $4.2 billion to Boeing and just over half that to SpaceX, which refashioned the capsule it was using to deliver station supplies.

If the mission goes well, NASA will alternate between SpaceX and Boeing for taxi flights, beginning next year.