CAPE CANAVERAL, Fla. (AP) -- After years of delays and stumbles, Boeing is finally poised to launch astronauts to the International Space Station for NASA.

It's the first flight of Boeing's Starliner capsule with a crew on board, a pair of NASA pilots who will check out the spacecraft during the test drive and a weeklong stay at the space station.

NASA turned to U.S. companies for astronaut rides after the space shuttles were retired. Elon Musk's SpaceX has made nine taxi trips for NASA since 2020, while Boeing has managed only a pair of unoccupied test flights.

Boeing program manager Mark Nappi wishes Starliner was further along. "There's no doubt about that, but we're here now."

The company's long-awaited astronaut demo is slated for liftoff Monday night.

Provided this tryout goes well, NASA will alternate between Boeing and SpaceX to get astronauts to and from the space station.

A look at the newest ride and its shakedown cruise:

White with black and blue trim, Boeing's Starliner capsule is about 10 feet (3 meters) tall and 15 feet (4.5 meters) in diameter. It can fit up to seven people, though NASA crews typically will number four. The company settled on the name Starliner nearly a decade ago, a twist on the name of Boeing's early Stratoliner and the current Dreamliner.

No one was aboard Boeing's two previous Starliner test flights. The first, in 2019, was hit with software trouble so severe that its empty capsule couldn't reach the station until the second try in 2022. Then last summer, weak parachutes and flammable tape cropped up that needed to be fixed or removed.

Veteran NASA astronauts Butch Wilmore and Suni Williams are retired Navy captains who spent months aboard the space station years ago. They joined the test flight after the original crew bowed out as the delays piled up. Wilmore, 61, is a former combat pilot from Mount Juliet, Tennessee, and Williams, 58, is a helicopter pilot from Needham, Massachusetts. The duo have been involved in the capsule's development and insist Starliner is ready for prime time, otherwise they would not strap in for the launch.

"We're not putting our heads in the sand," Williams told The Associated Press. "Sure, Boeing has had its problems. But we are the QA (quality assurance). Our eyes are on the spacecraft."

Starliner will blast off on United Launch Alliance's Atlas V rocket from Cape Canaveral Space Force Station. It will be the first time astronauts ride an Atlas since NASA's Project Mercury, starting with John Glenn when he became the first American to orbit the Earth in 1962. Sixty-two years later, this will be the 100th launch of the Atlas V, which is used to hoist satellites as well as spacecraft.

"We're super careful with every mission. We're super, duper, duper careful" with human missions, said Tory Bruno, CEO of ULA, a joint venture of Boeing and Lockheed Martin.

Starliner should reach the space station in roughly 26 hours. The seven station residents will have their eyes peeled on the approaching capsule. The arrival of a new vehicle is "a really big deal. You leave nothing to chance," NASA astronaut Michael Barratt told the AP from orbit. Starliner will remain docked for eight days, undergoing checkouts before landing in New Mexico or elsewhere in the American West.

Both companies' capsules are designed to be autonomous and reusable. This Starliner is the same one that made the first test flight in 2019. Unlike the SpaceX Dragons, Starliner has traditional hand controls and switches alongside touchscreens and, according to the astronauts, is more like NASA's Orion capsules for moon missions. Wilmore and Williams briefly will take manual control to wring out the systems on their way to the space station.

NASA gave Boeing, a longtime space contractor, more than $4 billion to develop the capsule, while SpaceX got $2.6 billion. SpaceX already was in the station delivery business and merely refashioned its cargo capsule for crew. While SpaceX uses the boss' Teslas to get astronauts to the launch pad, Boeing will use a more traditional "astrovan" equipped with a video screen that Wilmore said will be playing "Top Gun: Maverick."

One big difference at flight's end: Starliner lands on the ground with cushioning airbags, while Dragon splashes into the sea.

Boeing is committed to six Starliner trips for NASA after this one, which will take the company to the station's planned end in 2030. Boeing's Nappi is reluctant to discuss other potential customers until this inaugural crew flight is over. But the company has said a fifth seat will be available to private clients. SpaceX periodically sells seats to tycoons and even countries eager to get their citizens to the station for a couple weeks.

Coming soon: Sierra Space's mini shuttle, Dream Chaser, which will deliver cargo to the station later this year or next, before accepting passengers.

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