Prior to their launch on the first crewed mission of the Boeing Starliner next month, two US astronauts arrived at the Kennedy Space Centre in Florida on Thursday.

On 6 May, Butch Wilmore and Suni Williams, who have been waiting years to travel, will launch into space for a week-long stay on the International Space Station (ISS).

“It is extremely important that we are going to expand our agency's capacity to and from the Space Station with the Boeing Starliner launch,” Wilmore informed reporters.

Since 2020, NASA astronauts have travelled to and from the ISS via SpaceX's Dragon craft.

The US space agency has long hoped to add a second transportation provider, but Boeing has struggled with a number of delays in developing the Starliner.

The space capsule finally managed to arrive at the ISS in May 2022 —without a crew on board.

Now, it must carry out a crewed certification flight — which was originally scheduled for 2022 — before it can officially begin its transport missions.

Both astronauts have already visited the ISS, with Williams saying she has "all the confidence" in the ship and the mission control team.

“There is so much with... the capabilities of this spacecraft that other spacecraft don't have," Wilmore added.

The rocket that will propel the Starliner into space is an Atlas V by the United Launch Alliance (ULA), a joint venture between Boeing and Lockheed Martin.