For years, Elon Musk has talked about his goal of getting people to live on Mars. Now he's revealed how he plans to actually accomplish that.

Musk spoke on Tuesday about SpaceX's plan to get humans to the Red Planet--a mission that entails launching a reusable spaceship larger than any ship ever built, refueling it mid-flight, then blasting it to Mars, where its occupants will live. The ship would then be sent back to Earth and used again for the same purpose.

The talk came in front of a live audience at the International Astronautical Conference in Guadalajara, Mexico. In a speech live-streamed on YouTube, Musk spoke in his usual halting cadence, often struggling to slow down and explain the complex details of his grand plan.

Perhaps most important to the plan's success: getting the price of a one-way flight down to around $200,000.

"Not everyone would want to go," he said. "In fact, I think a relatively small number of people on Earth would want to go. But enough would want who could afford the trip that it would happen."

Getting to that price, though, presents possibly the biggest challenge. With current technology, Musk estimates that a trip to Mars would cost $10 billion per person. (The Apollo program, which sent 12 people to the moon, cost the U.S. government $200 billion in current dollars.) Hitting the $200,000 number amounts to reducing the price tag by 5 million percent.

So how to do it? About half the savings, Musk said, would come from being able to reuse the rockets and spaceships. Musk compared a single-use ship to Boeing 737s: If they were used only once, a plane ticket would have to run $500,000 for the manufacturer to just make its money back. Reusing can drastically slash that price. But these won't exactly be running with the frequency of the New York-Boston shuttle: Earth and Mars only align within the solar system every 26 months.

Musk's plan also calls for a spaceship that can be refueled while floating in Earth's orbit. A spaceship that lacks this ability, he says, would have to be five to 10 times larger and costlier. Once the ship is refueled, it can then blast toward Mars and coast at 62,000 mph. In all, the approximately 50-million-mile trip would take around 80 days.

To get the spaceship back to Earth, Musk plans to build a plant on Mars's surface for creating methane propellant.

The wildly ambitious plan would send 100 people to Mars at a time. He estimates that a full, self-sustaining civilization of 1 million people would be achievable somewhere between 40 and 100 years from the first trip, which he aims to complete in 2023.

"Timelines--I'm not the best at this sort of thing," Musk joked to the crowd. A Wall Street Journal report last month revealed that Tesla had missed more than 20 deadlines in the past five years, and Musk is notorious for pushing back events like rocket launches and big announcements.

Musk has long expressed the belief that overpopulation and limited resources would bring on the need for humans to become interplanetary. And while there's no telling how long that might actually take, he pointed out that it's a goal that requires continuous work if it's ever to be achieved. "I think what a lot of people don't appreciate is that technology doesn't automatically improve," he said. "It only improves if a lot of really strong engineering talent is applied to the problem."

To see what a 100-person journey to Mars might look like, check out the video SpaceX released Tuesday afternoon, which has all the makings (and better CGI) than a modern sci-fi movie.