Humanity could have an outpost on Mars just a decade from now, Elon Musk said.

Musk's company SpaceX is building a huge, reusable rocket-spaceship duo called the BFR to help our species explore and settle Earth's moon, Mars and other worlds throughout the solar system.

The billionaire entrepreneur's long-term vision involves the establishment of a million-person city on the Red Planet in the next 50 to 100 years. But we could get the founding infrastructure of such a settlement — an outpost Musk calls Mars Base Alpha — up and running much sooner than that, he said. [The BFR in Images: SpaceX's Giant Spaceship for Mars & Beyond]

"Probably 2028 for a base to be built," Musk said on Twitter Friday (Sept. 21), in response to a question about when Mars Base Alpha could graduate from artistic rendering to reality.

Musk's timelines are famously aggressive, and a lot would have to go right to hit that 2028 target. After all, the BFR (which stands for "Big Falcon Rocket") is still in the development phase. The first orbital flights of the 100-passenger spaceship and its giant booster probably won't come until 2020 or 2021 at the earliest, Musk said last week during an event at SpaceX headquarters in Hawthorne, California.

Neither Musk nor Maezawa revealed how much the latter is paying for the flight (though Maezawa did confirm that the artists will fly for free — he bought all the seats). But Musk said Maezawa has already made a substantial down payment and that his purchase is a big help in defraying the BFR's development costs. Those expenses will probably run around $5 billion when all is said and done, Musk said Friday.

"This has done a lot to restore my faith in humanity — that somebody's willing to do this — to take their money and help fund this new program that's risky, might not succeed [and] is dangerous," Musk said. "He is ultimately helping to pay for the average citizen to be able to travel to other planets. It's a great thing."

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