According to a Morgan Stanley analyst, Tesla CEO Elon Musk is on his way to becoming the world’s first trillionaire. But if that happens, it won’t be because of Tesla. Morgan Stanley analyst Adam Jonas said Musk’s passion project SpaceX would be what gets him there. Jonas said SpaceX is “challenging any preconceived notion of what was possible and the time frame possible”.

The first chartered SpaceX passenger flight launched last month. The flight marked the first time ever that no professional astronaut was aboard an orbit-bound rocket.

Musk, as well as SpaceX as a whole, have a long way to go before Musk can become a trillionaire. According to Bloomberg’s billionaires index, Musk is worth about $241 billion. Only 17 percent of his money comes from SpaceX.

The current biggest rival to Musk in the race to become the world’s first trillionaire is Amazon founder and former CEO Jeff Bezos. Bezos is second to Musk in net worth at $199 billion, and he has his own space passion project.

Blue Origin has flown two passenger flights. The most recent flight happened last week. It notably included “Star Trek” star William Shatner. Bezos himself was aboard the first Blue Origin flight, which launched in July.

“Best day ever,” Bezos said after the capsule touched down.

Musk and Bezos make up 2/3 of the ongoing billionaire space race. Virgin Galactic’s Richard Branson kicked off the U.S. portion of the space tourism boom riding his own rocketship to space nine days before the first Blue Origin flight. As of July, Virgin Galactic had sent crews into space four times. They had planned two more test flights from New Mexico before launching customers next year. By Blue Origin’s first flight, Virgin Galactic had more than 600 reservations to head to space at $250,000 apiece.