Boeing's Starliner launches its 1st astronaut-crewed flight after several delays

Boeing’s Starliner capsule launched Wednesday its first astronaut-crewed flight into space to the International Space Station (ISS) after several delays.

The liftoff occurred at 10:52 a.m. ET from the Cape Canaveral Space Force Station in Cape Canaveral, Florida.

Weather was 90% favorable to launch. Derrol Nail of NASA Communications said during a livestream that the team had been keeping an eye on the cumulus cloud forecast because if the rocket flies through cumulus clouds, it could create its own lightning strike.

About 15 minutes after the launch, the rocket separated from the spacecraft, allowing Starliner to fly on its own. At 11:24 a.m. ET, Boeing Space said Starliner had successfully reached stable orbit.

Starliner is designed to carry a seven-person crew, but aboard the "test drive" launch are NASA astronauts Barry “Butch” Wilmore, 61, a former U.S. Navy captain who will be commanding the flight, and Sunita Williams, 58, a former Navy service member who will be piloting the flight.

A team from United Launch Alliance (ULA), which manufactures and operates the rockets that launch spacecraft into orbit, began loading cryogenic propellant into the rocket before the planned liftoff early this morning in a sign of launch being all set to go.

Wilmore and Williams entered the capsule around 8:00 a.m. ET, taking their seats and performing a series of checks including communications checks and suit checks, according to a post on X from Boeing Space.

This flight will be Wilmore's third mission to the ISS, NASA said during its Wednesday livestream. Williams is also on her third flight to space and will be the first woman on a test flight in an orbital spacecraft, according to NASA.

After Starliner launches into orbit, it will be about a 24-hour journey to the ISS, during which the crew will test several flight objects, such as checking equipment, according to NASA.

Boeing Space said Wilmore and Williams will pilot Starline manually at certain points to prove it can, despite the spacecraft being able to operate autonomously.

Williams and Wilmore are expected to spend one week aboard the ISS and will be evaluating the spacecraft and its systems. Upon re-entry, the spacecraft will deploy parachutes and an airbag system, landing the pair in the western U.S.

It comes after the launch of Starliner was delayed several times. The crewed flight test was tentatively scheduled for May 6, but was scrubbed after a problem with an oxygen valve on the ULA rocket.

A new launch date had been set for May 25, but a small helium leak was discovered in the service module, which contains support systems and instruments for operating a spacecraft.

Another launch set for June 2 was scrubbed minutes before it was due to begin "due to the computer ground launch sequencer not loading into the correct operational configuration after proceeding into terminal count."

After Starliner launches into orbit, it will be about a 24-hour journey to the ISS, during which the crew will test several flight objects, such as checking equipment, according to NASA.

If the mission is successful, NASA could certify the spacecraft to perform routine missions to and from the ISS. NASA has primarily been using SpaceX's Dragon spacecraft to transport crew and cargo to the ISS.

The missions are part of the larger Commercial Crew Program at NASA, which uses American rockets and spacecraft to launch astronauts and cargo to the ISS with the hope of helping the federal space agency prepare for its upcoming moon and Mars missions.

ABC News' Gina Sunseri and Leah Sarnoff contributed to this report.