Elon Musk/SpaceX

SpaceX founder Elon Musk may have his heart set on the moon and Mars, but he hasn't forgotten about Earth.

The Starship spacecraft, currently in a very early stage of development, could potentially be used to ferry passengers from one city to another in less than an hour. But what would that feel like? Space Mountain, apparently.

Musk fielded questions about Starship on Twitter Wednesday, saying it could carry about 100 people to Mars with cabins, but would accommodate around 1,000 passengers for Earth-to-Earth flights where all seats are coach-style. Most trips of this sort would only take 15 to 20 minutes, so there would be no toilets or food prep areas on board.

"It's basically an ICBM traveling at Mach 25 that lands," Musk said. An ICBM is an intercontinental ballistic missile designed to deliver nuclear warheads at great distances.

But here's where it gets even more fun. A Twitter user asked Musk if passengers would be able to move around during the flight. He suggested Starship would need "a restraint mechanism like Disney's Space Mountain roller coaster."

That would be unwise. Probably needs a restraint mechanism like Disney’s Space Mountain roller coaster. Would feel similar to Space Mountain in a lot of ways, but you’d exit on another continent. — Elon Musk (@elonmusk) June 26, 2019

Space Mountain rides are located at most of the Disney theme parks. The roller coaster simulates a rocket trip into outer space. It uses a padded restraint that lowers down into the rider's lap.

Musk went on to say that Starship "would feel similar to Space Mountain in a lot of ways, but you'd exit on another continent."

SpaceX shared a concept video for its Earth-to-Earth launches in late 2017. It imagines Starship launching from and landing on platforms on water near major cities.

This sounds like an exciting alternative to airplanes, but potential passengers might be a little worried about Musk's coach-seats concept. Can we please get a little more leg room?