Nasa astronauts stranded in space until next year said they did not feel let down by Boeing, but admitted to “tough times”.

Boeing’s first astronaut mission ended earlier this month with its Starliner capsule returning to Earth with test pilots Barry “Butch” Wilmore and Sunita Williams still in space.

Mr Wilmore said they had “found some things that we just could not get comfortable with putting us back in the Starliner when we had other options”.

Nasa has said the pair will instead return on a SpaceX craft in February – stretching their original eight-day mission to more than eight months.

Speaking at a press conference on Friday evening from the International Space Station, Mr Wilmore said: “It’s been quite an evolution over the last three months, we’ve been involved from the beginning through all the processes of assessing our spacecraft, Calypso.

“And it was trying at times. There were some tough times all the way through.

“You certainly, as the commander and the PLT (pilot) of your spacecraft, you don’t want to see it go off without you, but that’s where we wound up.”

Asked if he felt let down by Boeing after Starliner returned to Earth without its crew, Mr Wilmore said: “Let down? Absolutely not.

“Never entered my mind. I don’t think Suni’s either, until you mentioned it.”

Mr Wilmore added that Boeing was “on board” with “changes that need to be made” after the company’s Starliner capsule returned to Earth without its crew.

The astronaut told the press conference: “Obviously, when you have issues like we’ve had, there’s some changes that need to be made.

“Boeing’s on board with that. We’re all on board with that.”

Mr Wilmore added: “When you push the edge of the envelope again and you do things with spacecraft that have never been done before, just like Starliner, you’re going to find some things.

“And in this case, we found some things that we just could not get comfortable with putting us back in the Starliner when we had other options.

“There’s many cases in the past where there have not been other options.

“We were very fortunate that we have the Space Station and that we had the option to stay and we had the option to come back a different way.”

Ms Williams, whose hair floated during the press conference, said the pair missed their families during their extended stay on the International Space Station.

The astronaut added: “I miss my two dogs, I miss my friends.

“But you know what? Like Butch said, there are so many people on Earth that are sending us messages.

“And it makes you feel just right at home with everybody when we’re able to have those conversations with our friends and family at home.”