The Falcon Heavy may be a remarkable rocket, particularly after its successful maiden launch on Tuesday, but Spacex has something more impressive on the horizon: the BFR.

The BFR — officially the “Big Falcon Rocket,” though at first the F stood for a much more crude word — will be a monster that SpaceX CEO and founder Elon Musk hopes will take humans to Mars.

The will be composed of two stages: the booster and the Ship. The ship’s payload bay, where people and cargo go, will be eight storeys tall.  Musk unveiled the idea last year. The first one is now under construction. 

“We think the new BFR architecture is a better way to go,” because of its reusability, Musk said in a news briefing on Tuesday. 

“BFR is really designed for being able to launch every few hours, whereas the Falcon architecture is designed to be able to launch every few days in an optimal situation.”

The Falcon Heavy hasn’t been approved by the U.S. government to carry people, though it was expected to take up two private citizens who paid for a trip around the moon. Musk said on Tuesday they’ll likely hitch a ride on the BFR instead. 

Musk said work on the BFR has progressed fairly rapidly and that it could be ready within the year, though he has a reputation for missing delivery dates.

The challenge, he says is the ship. In the case of the moon flyby, that’s not as important. However, if the ship is to land on Mars, it’s going to have to be capable of enduring many different atmospheric pressures.

“It’s got to control itself through a wide regime of everything from vacuum to rarified gas to thin atmosphere, thick atmosphere, hypersonic, supersonic, transonic, subsonic, different types of atmosphere on different planets and then land on unapproved terrain. That a pretty ridiculous set of requirements,” he said.

And if you’re picturing an interior like the cramped insides of an Apollo spacecraft, think again: The ship will have cabins, a galley and an entertainment area. Musk said previously a Mars-ready BFR would have 40 cabins, with between two and six people in each.

Another advantage to this new rocket will be its ability to refuel. To go to Mars, the BFR would launch with people. The booster would then return to Earth, take up another ship loaded with fuel, and rendezvous with the first ship. 

The farther you go, the more fuel you need. The more fuel you need, the more your rocket has to lift, and that increases costs substantially. The reloading potential allows SpaceX to keep the cost down.

Musk has also proposed using the rocket to transport people around the globe, with most long-distance trips completed in less than half an hour, as seen in the SpaceX animation below.