Britain's Prince William ignited controversy on Thursday by blasting space tourism and saying that more attention should be paid to problems closer to home ahead of the COP26 climate summit.
The comments by Queen Elizabeth II's grandson were scheduled to be aired in a BBC interview later Thursday, a day after 90-year-old "Star Trek" star William Shatner became a real space traveller on Blue Origin's second crewed mission.
The company's maiden human flight in July had included its founder Jeff Bezos of Amazon and was seen as a breakthrough for the emerging space tourism sector.
But Prince William said: "We need some of the world's greatest brains and minds fixed on trying to repair this planet, not trying to find the next place to go and live."
Virgin Galactic, which offers a similar experience of a few minutes of weightlessness and a view of the Earth's curvature from the cosmos, launched its founder Richard Branson in July, a few days before Bezos.
The comments by William, second in line to the UK throne, were rebuffed by critics who pointed to the scientific value of mankind's decades-old forays into the final frontier.
British space scientist and broadcaster Maggie Aderin-Pocock said she agreed with William that humanity had made a "mess" of Earth, and had to learn the lessons.
"But it can't be our only focus. Space is inspirational. Because of 'Star Trek', I became a space scientist, now I work on climate change," she said on ITV.
"I'm going to COP26 next month to talk about how space is helping us with climate change. So yes, we need to focus on climate change, but it can't be the only thing."
The group Republic, which campaigns to abolish Britain's monarchy, said William should "keep his ill-informed opinions to himself".
"This is politics, and while space tourism is questionable, science benefits from space exploration," it tweeted.
"We may agree or disagree, but lectures from a hypocrite who can't be properly challenged are a real problem."
- 'Ahead of the curve' -
William was speaking ahead of the inaugural Earthshot Prize awards ceremony on Sunday, his initiative to honour those working on environmental solutions.
Looking ahead to the COP26 summit in Glasgow, which begins on October 31, he warned world leaders against "clever speak, clever words, but not enough action".
"It would be an absolute disaster if (son) George is sat here talking to you... in like 30 years' time, still saying the same thing, because by then we will be too late."
William's father Prince Charles, a lifelong environmentalist, has also spoken out on the need for action from the leaders rather than words in the build-up to the UN climate summit.
"He's had a really rough ride on that, and I think you know he's been proven to being well ahead of the curve, well beyond his time in warning about some of these dangers," William said.
"But it shouldn't be that there's a third generation now coming along having to ramp it up even more."
Queen Elizabeth, Charles and William are all due to attend events at the two-week summit.
The gathering will try to persuade major developing economies to do more to cut their carbon emissions, and get the rich world to cough up billions more to help poorer countries adapt to climate change.
"I want the things that I've enjoyed -– the outdoor life, nature, the environment -– I want that to be there for my children, and not just my children but everyone else's children," William said.
"If we're not careful we're robbing from our children's future through what we do now. And I think that's not fair."