SpaceX's Mars ships won't be ferrying just the super rich to and from the Red Planet, if everything goes according to Elon Musk's plan.

The price of a seat aboard SpaceX's Starship interplanetary vehicle will eventually drop enough to be accessible to a large chunk of the industrialized world's population, the billionaire entrepreneur predicted over the weekend.

"Very dependent on volume, but I'm confident moving to Mars (return ticket is free) will one day cost less than $500k & maybe even below $100k. Low enough that most people in advanced economies could sell their home on Earth & move to Mars if they want," Musk wrote on Twitter Sunday night (Feb. 10). [Images: SpaceX's Giant Spaceship for Mars Colony & Beyond]

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Very dependent on volume, but I’m confident moving to Mars (return ticket is free) will one day cost less than $500k & maybe even below $100k. Low enough that most people in advanced economies could sell their home on Earth & move to Mars if they want. — Elon Musk (@elonmusk) February 11, 2019

The 100-passenger Starship will launch to Earth orbit atop a huge rocket called Super Heavy, then make its own way to Mars (or the moon, or whatever its final destination may be — the ship could go many places in the solar system, Musk has said). Super Heavy will return to Earth, make a vertical landing and fly again — many more times, in fact.

Indeed, rapid and repeated reuse of both Starship and Super Heavy is key to Musk's vision of ambitious but affordable spaceflight. Also helping in this regard, he said, is a recent Starship design tweak: building the vehicle out of stainless steel rather than pricier carbon-composite material, as originally planned.

"This will sound implausible, but I think there's a path to build Starship/Super Heavy for less than Falcon 9," Musk wrote in another tweet Sunday night, referring to SpaceX's workhorse Falcon 9 rocket. He then replied, "Yes," when one of his Twitter followers asked if the switch to stainless steel was an important factor in this potential price reduction.

SpaceX is aiming to launch its first Mars missions with Starship and Super Heavy in the mid-2020s. But a Starship prototype could get off the ground very soon. SpaceX has already built a small-scale "hopper" and plans to launch that vehicle on its first test flight in the coming weeks or months.

The hopper won't get anywhere near Mars, though; it will test the Starship design on brief flights in Earth's atmosphere.

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