Watch Boeing Starliner make another attempt to launch NASA astronauts

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Boeing aims to launch its first Starliner flight with astronauts on Wednesday, in the latest attempt to fly the long-delayed spacecraft.

The launch is scheduled for 10:52 a.m. ET from Cape Canaveral, Florida. Two NASA astronauts will be aboard the Starliner capsule, which will be carried by United Launch Alliance's Atlas V rocket to the International Space Station.

Wednesday is the latest in a series of attempts to launch the mission, which is known as the Boeing crew flight test. On Saturday, a launch attempt was called off in the final minutes of the countdown due to a problem with one of the computer's that provides ground support to the rocket. In early May, another attempt was called off due to an issue detected with the rocket itself.

If the launch is postponed again, Boeing has a backup opportunity scheduled for Thursday.

United Launch Alliance – or ULA, a joint venture of Boeing and Lockheed Martin – replaced the rocket's problematic valve after the May attempt and replaced a faulty part in the ground infrastructure computer after Saturday's attempt.

Butch Wilmore and Suni Williams are flying on Starliner, with the former serving as the spacecraft's commander and the latter as its pilot.

Wilmore joined NASA in 2000 and has flown to space twice previously on the Space Shuttle and Russia's Soyuz. Before NASA, Wilmore was a U.S. Navy pilot.

Williams was selected by NASA in 1998 and has also flown to space twice before, on the Space Shuttle and then the Soyuz. Williams was also a Navy pilot, like Wilmore, before joining the space agency.

Starliner launches on ULA's Atlas V. The rocket debuted in 2002, and the Starliner crew flight test represents its 100th launch.

The capsule itself is built to carry as many as four NASA astronauts per flight and more than 200 pounds of research and cargo. The spacecraft lands using a parachute and airbag system. Starliner is reusable, with each capsule designed to fly as many as 10 missions.

Boeing's crew flight test aims to certify the Starliner system as capable of carrying NASA astronauts to and from the ISS.

If Starliner launches on Wednesday, it will fly in space for about 25 hours before a planned docking with the International Space Station at 12:15 p.m. on Thursday. The astronauts will then spend about a week on the ISS, focused on testing Starliner, before returning to Earth.