Billionaire Bill Gates has said he would rather pay for vaccines than travelling to Mars, which he does not think is a good use of money.
"It's actually quite expensive to go to Mars. You can buy measles vaccines and save lives for $1,000 (£814) per life saved," he told the BBC.
"And so [that] just kind of grounds you, as in - don't go to Mars."
Fellow entrepreneur Elon Musk has said he wants to colonise Mars, while Jeff Bezos has also joined the "space race".
SpaceX, the rocket company co-founded by Mr Musk in 2002, has made it an ultimate goal to send crewed flights to Mars and eventually colonise the Red Planet.
Mr Bezos, the founder of Amazon, heads the aerospace company Blue Origin and made a short journey to space in 2021, while British tycoon Sir Richard Branson has also reached the edge of space on his Virgin Galactic rocket plane.
Mr Gates, the co-founder of Microsoft, also believes artificial intelligence will "pretty dramatically" transform humanity.
He said: "It will help us look into medical and scientific questions. It's not just robots, it's helping to read and write as well.
"In fact, there's been more progress there than on the robotic side. Both of them will give us much higher productivity."
Credit: BBC world news