New attempt Saturday to launch first manned flight of Starliner spacecraft

After the first attempt was scrubbed at the last minute in early May, a second attempt will be made Saturday to launch Boeing's Starliner spacecraft on its first manned flight to the International Space Station.

The vehicle is scheduled to lift off from Cape Canaveral, Florida, at 12:25 p.m. Saturday (16:25 GMT) under what is expected to be favorable weather conditions.

The Starliner crew consists of NASA astronauts Butch Wilmore and Sonny Williams. It will be launched by a United Launch Alliance Atlas V rocket.

Ten years ago, NASA requested two new vehicles from the American companies "Boeing" and "SpaceX" to transport its astronauts to the International Space Station, in order to stop relying on Russian vehicles.

While SpaceX has been playing the role of carrier into space for four years, Boeing has faced a series of setbacks that have led to years of delays.

Having recently suffered safety problems with its commercial aircraft, the American company is staking its reputation on this test mission to prove that its vehicle is safe before it begins its regular missions to the International Space Station.

The mission is also important for NASA, as the availability of a second vehicle will allow it to better manage any emergency situations that may arise.

Earlier last month, the Starliner's launch was scrubbed at the last minute while the two astronauts were in their launch position inside the vehicle due to a rocket valve problem that was later repaired.

A limited leak of helium into the vehicle was then detected. But Boeing and NASA decided not to fix it, because doing so would require separating the Starliner from the launch pad.

"We believe we can manage this leak by monitoring it before launch and even if it increases during flight," Steve Stich, manager of NASA's commercial human spaceflight program, said Friday.

This setback is the latest in a series of unpleasant surprises for Boeing.

In 2019, during the first unmanned test, the capsule failed to stay on course and returned to Earth without reaching the International Space Station.

In 2021, when the rocket was on the launch pad, malfunctions occurred that prevented the capsule's valves from working, causing another postponement of the mission.

The vehicle was finally able to arrive at the International Space Station empty in May 2022.

Other problems were later discovered, most notably with the parachutes that slowed the capsule during its return to the atmosphere, again delaying the first manned flight.

The Starliner is scheduled to dock with the International Space Station at about 17:50 GMT on Sunday for a mission that will last about a week before the two astronauts return to Earth.

Butch Wilmore, 61, and Sonny Williams, 58, have visited the space station twice before, first on the space shuttle and then on a Russian Soyuz spacecraft.

But this time their mission will be to test an entirely new vehicle. The two astronauts, both from the U.S. Navy, helped develop the vehicle.

Once in space, the two astronauts will drive the vehicle manually.

The vehicle also carries some last-minute equipment to repair the system that recycles the astronauts' urine and turns it into water.

One of the pumps suddenly stopped working this week, and urine must be stored in the vehicle until it is repaired, knowing that its capacity is limited.

Few American vehicles have transported astronauts before.

After the space shuttle program was retired in 2011, NASA astronauts relied on Russian Soyuz vehicles.

In 2014, NASA signed fixed-price contracts with SpaceX ($2.6 billion) and Boeing ($4.2 billion) to develop the two spacecraft.

SpaceX surpassed Boeing by carrying astronauts to the space station for the first time on one of its vehicles in 2020.

Once the Starliner is operational, NASA plans to alternate between SpaceX and Boeing vehicles to transport astronauts to the station.

As the International Space Station nears retirement in 2030, SpaceX and Boeing vehicles will be used to transport humans to future private space stations that many companies have begun planning to build.