The CST-100 Starliner mission is not expected to take place until July 21, officials from both entities said.

"We discussed and decided that the best launch attempt would not be until July 21" for the crewed test flight, Steve Stich, head of NASA's manned commercial program, told reporters.

The US space agency wants to set up a second means of transport to the ISS for its astronauts, with the SpaceX capsule already in service.

But Boeing has suffered a series of setbacks that have significantly delayed its program, including a failed test flight in 2019. The company finally managed in May 2022 to reach the ISS for the first time – without a crew on board.

Boeing had then hoped to be able to make its first manned flight in 2022, before it was postponed a first time to February 2023, then April.

"We're pretty confident about that date" of July 21, said Mark Nappi, head of Boeing's Starliner program.

According to Steve Stich, more time is needed to certify the parachute system designed to safely return the astronauts and the capsule to Earth. A ground test of the parachutes will be conducted in May.

The Starliner capsule will carry two NASA astronauts, Barry Wilmore and Sunita Williams, to the ISS where they are expected to stay for at least eight days.

The launch will be using an Atlas V rocket (manufactured by the United Launch Alliance consortium) from Cape Canaveral in Florida.

If the mission is successful, Boeing's capsule can finally be certified and begin operational flights, at a date yet to be determined.

NASA signed fixed-price contracts with both SpaceX ($2.6 billion) and Boeing ($4.2 billion) in 2014.

By using two companies, it wants to diversify its options, so as never to risk finding itself without American means of transport, as after the shutdown of the space shuttles in 2011. Until SpaceX, NASA was indeed reduced to paying for places in Russian Soyuz rockets.

Elon Musk's company, a newcomer to the aerospace industry compared to Boeing, has already transported 18 astronauts to the ISS with its own capsule, Dragon -- as well as four private passengers, on a space tourism mission.

© 2023 AFP