Liftoff of the SpaceX Falcon Heavy rocket. (GeekWire Photo/Kevin Lisota)

Elon Musk’s SpaceX is aiming to raise up to $507 million in a new funding round, according to documents filed with the state of Delaware last week.

SpaceX has authorized 3 million shares of stock for this Series I round, valued at $169 each, according to documents provided to GeekWire by Lagniappe Labs, creator of the Prime Unicorn Index. The round could bring SpaceX to a valuation of approximately $23.7 billion if all shares are sold.

This new round follows a big raise last year. In November, SpaceX landed $100 million as part of a larger $450 million round.

SpaceX is coming off the successful launch of the Falcon Heavy rocket in February that captivated the nation in a way that harkened back to the early days of the space race. But Musk has come to see Falcon Heavy primarily as a transitional step to an even more powerful launch vehicle, known as the BFR (which stands for Big Falcon Rocket or Big F***ing Rocket to others).

BFR is SpaceX’s first Mars transport vehicle. But Musk plans to use BFR as an all-purpose space vehicle — for trips ranging from point-to-point suborbital passenger travel, to orbital satellite deployment, to moon missions and more. The company is making progress toward short-hop test flights on Earth by the middle of next year, with a timeline calling for the first cargo flights to head for Mars in 2022.

These massive funding rounds show why space travel today is largely being pursued by the world’s wealthiest geeks. Musk’s net worth is $19.4 billion. Jeff Bezos, the world’s richest person, says he sells about $1 billion worth of his Amazon stock annually to put toward his Blue Origin space venture.

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