Oprah Winfrey cried tears of pride when Gayle King flew into space.

The media mogul was seen looking emotional when her best friend joined an all-female crew on a Blue Origin flight earlier this month, but the 70-year-old presenter dismissed speculation her pal was worried about her, insisting Oprah wept because she knew "what it took" for Gayle to take part.

Gayle told E! News: "She was so welled up. I know she said at one point [that] she was proud of me.

"When people saw her crying, people said, 'Oh, she's so worried. She thinks something's gonna happen.'

"That wasn't it at all. She was crying because she knew what it took for me to do that, and so when I came [back] she was saying, 'I'm so proud of you. You did that and I'm so proud of you.'"

Gayle insisted Oprah always had faith in the trip and the crew, which also included pop star Katy Perry, Jeff Bezos' fiancee Lauren Sanchez, aerospace engineer Aisha Bowe, civil rights activist Amanda Nguyen, and film producer Kerianne Flynn.

She added: "She always said I was gonna be OK. And Oprah knows things."

Gayle previously admitted she was "disappointed and saddened" by critics, who had branded the 11-minute flight "frivolous".

Speaking on 'CBS Mornings', she said: "Space is not an either or, it's a both and, and because you do something in space doesn't mean you're taking anything away from Earth. And what you're doing in space is trying to make things better here on Earth.

"What Blue Origin wants to do is take the waste here and figure out a way to put it in space to make our planet cleaner. Jeff Bezos has so many ideas, and the people that are working there are really devoted and dedicated to making our planet a better place. That's number one.

"There was nothing frivolous about what we do.

"So, you know, I'm very disappointed and very saddened by it [the criticism]. And I also say this -- what it's doing to inspire other women and young girls? Please don't ignore that. I've had so many women and young girls reach out to me, and men too, by the way. Men too that say, 'Wow, I never thought I could do that, but I see you doing it at this stage of your life.' "