Speaking at the International Astronautical Congress (IAC) in Adelaide, Australia, last week, SpaceX CEO Elon Musk made it clear he still has his sights set on colonizing the red planet.

But here's something else that's becoming apparent: Along the way, he wouldn't be averse to making a pit stop at the moon.

Rendering of SpaceX "BFR" standing on the Moon

Artist's conception of SpaceX BFR rocket ship standing upright on the moon. Image source: SpaceX.

Destination moon

Musk, the founder of rocket launch company SpaceX, has been talking for years about wanting to establish a human colony on Mars. His interest in Earth's moon, however, appears to be a bit more recent in the making. We first started to pick up hints of this back at last year's IAC conference in Guadalajara, Mexico, when Musk mused: "We could conceivably go to the moon, and I have nothing against going to the moon."

(Of course, he then proceeded to lay out all the things he has against going to the moon: The fact that "It doesn't have any atmosphere," for example, that "it's not as resource-rich as Mars," and that "it's got a 28-day day").

That said, Musk did note that thanks to the "propulsive lander" system on his Dragon spaceship, "you can go anywhere in the solar system. [You can] go to the moon." And just a few months later, he appeared to be warming to the idea. Speaking at the International Space Station Research and Development Conference in Washington, D.C., in July, Musk urged NASA: "If you want to get the public fired up, you've got to put a base on the moon."

Building a better moon rocket

Now, Musk thinks he has a way to help get folks get to the moon economically. Addressing the issue in Adelaide, Musk touted the benefits of SpaceX's latest project -- the BFR -- for potential moon landings.

"In order to land on a place like the moon where there is no atmosphere and certainly no runways," Musk reminded his audience in Adelaide, "propulsive landing" is "key." With no atmosphere to support the wings on an airplane-like lander, a spaceship must be able to brake its descent by firing retrorockets such as those installed on SpaceX's Dragon lander (and on the upcoming BFR).

To further facilitate BFR's usefulness on moon missions, Musk explained that SpaceX is designing this spaceship to launch into Earth orbit, there to be refilled from a separate tanker rocket. With a full tank of (methane) gas, BFR will have sufficient fuel to travel to the moon, land, relaunch, return to Earth, and land again. This, says, Musk, will "enable the creation of Moon Base Alpha, or some sort of lunar base."

Best of all, BFR will be a much bigger rocket than anything in SpaceX's fleet of Falcon 9 rockets, and bigger even its planned Falcon Heavy -- able to carry much more equipment to build a moon base, and much more economically than anything NASA has had access to in the past. If Falcon 9 is rated to carry payloads of roughly 4 tons to Mars, and Falcon Heavy can carry just under 17 tons, SpaceX is designing BFR to tote payloads of up to 150 tons on interplanetary trips -- a 37-fold improvement over the capability of SpaceX's current rockets.

The moon on Musk's mind

To emphasize his change of heart on the idea of building a moon base, Musk drove the point home:

It's 2017. I mean, we should have a lunar base by now. What the hell is going on?

But is Musk using the royal "we" when discussing the moon? He talked a lot in Adelaide about BFR's usefulness for facilitating the construction of a moon base (including its ability to go from Earth to moon and back without needing to refuel at a lunar gas station that has yet to be built). What Musk did not clearly say is that SpaceX itself plans to finance the creation of a moon base.

Rather, Musk's plan may be to gin up enthusiasm for the idea of a moon base, in hopes NASA will pay for a lunar expedition -- and hire SpaceX to provide the transportation there and back (providing SpaceX with much-needed capital to finance Musk's real goal of getting to Mars in the process). If that's Musk's endgame, though, then he may run into some competition.

Earlier this year, Jeff Bezos at Blue Origin offered much the same idea of running cargo to the moon on NASA's behalf. Bezos suggested a willingness to build a "Blue Moon" lunar lander for NASA, and to partner with Space Launch System builders Boeing and Lockheed Martin for the trip. Alternatively, Bezos is building a big rocket ship of his own, "New Glenn," which once developed should permit Blue Origin to visit the moon without the help of Boeing and Lockheed.

Meanwhile, despite all of Musk's and Bezos' talk of building a base on the moon, NASA's latest thoughts seem to be turning more toward building a space station in orbit around the moon, instead. We'll have to see whether the corporate titans can persuade the government to take the more aggressive step toward an entrenched lunar presence.