Elon Musk has updated his timeline for humans colonising Mars.
The world's richest man has often talked about getting a SpaceX rocket full of humans to the red planet but his earlier predictions may have been overly optimistic.
He told CNBC earlier this year that he was "highly confident" the company would land humans on Mars by 2026.
But the controversial billionaire told the Lex Fridman Podcast this week the company might be there in "as little as five years", but that was a best case scenario.
In the worst case it would take another 10 years, he said.
Musk told Fridman that SpaceX's Starship rocket is the "most complex and advanced rocket that's ever been made" and engineering it was one of the determining factors for the timescale.
That work will currently cost trillions of dollars but he told Fridman he was working on getting the cost down.
"The fundamental optimisation of Starship is minimising the cost per tonne to orbit and ultimately cost per ton to the surface of Mars," he said.
The Tesla founder also gave an update on the company's much-derided robot to Fridman, saying the Tesla Bot could be an "incredible buddy like C3PO or R2D2".
"I think the possibilities are endless," he said.
"It's not quite in Tesla's primary mission directive of accelerating the world's transition to sustainable energy, but it's an extremely useful thing for the world to make a humanoid robot that is capable of interacting with the world and helping in many different ways.
"It could develop a personality over time that is unique."
