"What I want to try to achieve here is to make Mars seem possible," Musk said during a presentation on Tuesday at the International Astronautical Congress meeting.
The idea behind this spacecraft, Musk said, is to make humans a multi-planetary species.
How the Interplanetary Transport System works
Here's the size of the ITS compared to a human:
Then the booster will return to Earth:
It will then launch a second time, carrying a tanker full of rocket propellant. It will refuel the spacecraft while it's in orbit. The tanker and spacecraft look almost identical to keep the cost of development down:
The tanker will return to Earth, and the spacecraft will take off for Mars. In addition to the propellant, the spacecraft will be powered by solar arrays:
The spacecraft will have a heat shield to protect it as it descends on Mars.
"The heat shield is basically a giant break pad," Musk said.
The ITS will eventually carry humans to Mars and even farther destinations.
What it will take to get to Mars
Using traditional methods, a trip to Mars right now would cost about $10 billion per person, according to Musk.
"That is a steep price to pay for a ticket," Musk said.
We can't create a civilization with that price tag. We have to improve the cost by 5 million percent, Musk estimates, before we can create a sustainable civilization.
In order to do that, SpaceX hopes to design reusable rocket parts and a way to refill the spacecraft in orbit.
Refilling in orbit makes it possible to design a smaller, and therefore cheaper, spacecraft, since you won't have to load as much fuel on board, Musk said. Once the spacecraft gets to Mars, he added, we can create rocket fuel there to power the spacecraft for its return trip.
At first, the ITS will carry about 100 people in one trip, but Musk says 200 or more will eventually be possible.
The first colony flights could happen within 10 years if everything goes perfectly, Musk said.
What will the trip be like?
The trip itself is designed to be "fun," Musk said. The spacecraft is set up with zero-gravity games, movie screens and even a restaurant.
Tickets will be less than $200,000, and could drop to $100,000 over time, Musk said.
If we set up refueling stations for the ITS along the way, "you can actually go anywhere in the solar system by planet-hopping or moon-hopping," Musk said.
You can watch the whole animation of the ITS design below:
Sept. 27, 2016, 4:07 p.m.: This post has been updated.