Elon Musk has already sent a Tesla Roadster to orbit on a SpaceX rocket, and Wall Street is looking for more crossovers between the two companies.

The billionaire has hinted at flying-car ambitions but has the same concerns as analysts, regulators, and citizens: safety.

Morgan Stanley says Tesla's expertise in batteries, AI, charging and material science gives it a clear leg up on the competition.

Elon Musk's SpaceX helped the Boring Company build its first tunnel, and it could be far from the last of the billionaire's companies to benefit from another's expertise.

Adam Jonas, an autos analyst at Morgan Stanley who regularly dabbles in the extra-terrestrial, sees a potential partnership between Tesla and SpaceX that helps flying cars become less "Jetsons" and more real-world.

"Tesla has expertise in batteries, AI software, complete vehicle engineering, charging infrastructure and material science that we believe may have transferability to the autonomous aircraft domain," he said in a note to clients in December.

Musk, too, has voiced his excitement for flying cars — but with more caution.

"Obviously, I like flying things," the billionaire told Bloomberg in 2017. "But it's difficult to imagine the flying car … If somebody doesn't maintain their flying car, it could drop a hubcap and guillotine you. Your anxiety level will not decrease as a result of things that weigh a lot buzzing around your head."

There are plenty of obstacles between today's highways and skies filled with buzzing drones for delivering people, packages, and more. Still, Morgan Stanley estimates that 830,000 will be flying through the skies in the US alone by 2040 — accompanied by a "significant regulatory risk."

And a Tesla-SpaceX crossover could also help Musk avoid future headaches surrounding the automaker's life as a public company. Last year, the CEO tried and failed to take Tesla private, but hasn't ruled it out in the future.

On an earnings call last year, Musk touted a "cross-fertilization of knowledge from the rocket and space industry to auto back and forth," adding that "it's really been quite valuable."

Until then, Wall Street analysts will be watching for more Tesla Roadsters to launch on SpaceX rockets, and paying careful attention to any other cross-overs.

"We would describe the current state of technology for electric autonomous aircraft as underdeveloped, but rapidly improving in areas of pilot substitution, safety, and efficiency," Jonas wrote.