SpaceX aims to launch its first cargo mission to Mars in 2022 and send people toward the Red Planet just two years after that. Those are just two of the highlights of the company's current Mars-colonization plan, which SpaceX founder and CEO Elon Musk unveiled early Friday morning EDT (Sept. 29) at the 68th International Astronautical Congress (IAC) in Adelaide, Australia.

Musk's talk — which took place Friday afternoon local Adelaide time — served to update the architecture the billionaire entrepreneur revealed at last year's IAC, in Guadalajara, Mexico. That previous presentation introduced a huge, reusable rocket-spaceship combo called the Interplanetary Transport System (ITS), which Musk envisioned helping to establish a million-person city on Mars within the next 50 to 100 years. [The BFR: SpaceX's Mars-Colonization Architecture in Images]

As Musk described it last year, the roughly 40-foot-wide (12 meters) ITS booster would feature 42 Raptor engines. It would launch the spaceship to Earth orbit, then come back down to its pad for a pinpoint landing — and another flight in quick succession. The spaceship, meanwhile, would be fueled in orbit by a tanker (which would also be launched by an ITS booster).

The ITS spaceships would linger in orbit until the time was right to depart for Mars, when they would do so en masse. (Such windows come along once every 26 months.) Each ship would be capable of carrying about 100 people to the Red Planet; after landing there and offloading their cargo and passengers, the ships would top up their tanks on the Martian surface with locally produced propellant (methane and oxygen) and then launch back to Earth.

 

The new plan retains this same basic idea, but with some important tweaks. For example, the rocket has been scaled back a bit; it will now be about 30 feet (9 wide) and sport "just" 31 Raptor engines. (For comparison, the first stage of SpaceX's in-service Falcon 9 rocket has nine Merlin engines.) And the name "ITS" seems to be out: During Friday's talk, Musk repeatedly referred to the system by the "code name" BFR, which is short for Big F***ing Rocket.

But the most important change has to do with the system's affordability, Musk said Friday.

"In last year's presentation, we were really searching for what the right way — how do we pay for this thing?" he said. "We went through various ideas — do a Kickstarter, collecting underpants. These didn't pan out. But now we think we've got a way to do it."

The answer, he explained, lies in downsizing the system a bit and using it for everything that SpaceX does, from satellite launches to International Space Station resupply flights to crewed Mars missions. In other words, the company plans to put its Falcon 9 and Falcon Heavy rockets — the latter of which hasn't even flown yet — and its Dragon capsule out to pasture relatively soon.

"If we can do that, then all the resources that are used for Falcon 9, Heavy and Dragon can be applied to this system. That's really fundamental," Musk said. "We believe that we can do this with the revenue we receive for launching satellites and for servicing the space station."

SpaceX will, however, "build ahead" and keep a stock of Falcon 9s and Dragons around for a while, in case customers wish to use those vehicles during the early days of BFR operation...