Speaking at the International Astronautical Congress in the western Mexican city of Guadalajara, Musk showed a futuristic video depicting his ideas for an interplanetary transport system based on re-usable rockets, a propellant farm on Mars and 1,000 spaceships on orbit, carrying about 100 people each.
The spacecraft would have a restaurant, cabins, zero-gravity games and movies.
"It has to be fun or exciting. It can't feel cramped or boring," he said.
Millions of tons of cargo would also need to blast off aboard a powerful rocket, which he described as a "scaled-up version of the Falcon 9 booster," the company's current rocket system that can land vertically.
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Reducing cost would be another key hurdle to establishing a human civilisation on Mars, he said before an overflow crowd at an expo center with a few thousand seats.
"We aim to improve the cost per ton to Mars by five million per cent," Musk said.
SpaceX has said it plans to send an unmanned Dragon cargo capsule to Mars as early as 2018, paving the way for a human mission that would leave Earth in 2024 and arrive on the Red Planet the following year.