In December, a giant white tent appeared at the Port of Los Angeles. A routine permit suggested that SpaceX, the rocket company founded by Elon Musk, was using the roughly 6,000-square-metre facility as a “storage tent.”

But Musk revealed the tent’s true purpose a few months later. Inside, his engineers are building a colossal interplanetary spacecraft called BFR, the Big Falcon Rocket (or, as Musk has said, Big F—ing Rocket).

On Thursday, SpaceX announced it had selected the first private passenger to be launched in the BFR. That person, whose identity is set to be revealed this week, will fly around the moon, the company said.

The BFR project and its immediate lunar goalposts mark the incredible and plainly unorthodox beginning of an effort by SpaceX to colonise Mars. Though Musk may announce a moon-mission launch date on Monday, his larger goal, which he has described as “aspirational,” is to launch an uncrewed cargo mission to the red planet in 2022, followed by human missions in 2024.

“He wants to have two planets for humans to live on. Some people call it crazy, but it kind of makes some sense,” Marco Cáceres, a senior space analyst at the Teal Group, told Business Insider. “If something were to happen to our planet, we have an option.”

The two-part BFR, as described by Musk before his private-lunar-voyage announcement, will consist of a  50m-tall spaceship sitting atop a 58m-tall rocket booster. Together, such a system would be 35 storeys. When fully fuelled, it’ll weigh nearly 4 million kilogrammes, lift up to 150 tons of cargo, and ferry those supplies to Mars with as many as 100 passengers. On top of all that, the entire system will be 100% reusable. That’s something “we haven’t seen, ever,” Cáceres said. “This would be the first entirely reusable launch vehicle.”