Elon Musk may be focused primarily on Mars, but he'd also like to see a human outpost on a world much closer to home.

"To really get the public real fired up, I think we've got to have a base on the moon," the billionaire founder and CEO of SpaceX said today (July 19) at the 2017 International Space Station Research and Development (ISSR&D) conference in Washington, D.C.

"Having some permanent presence on another heavenly body, which would be the kind of moon base, and then getting people to Mars and beyond — that's the continuance of the dream of Apollo that I think people are really looking for," Musk told NASA ISS program manager Kirk Shireman, who interviewed him onstage at the conference. [Moon Base Visions: How to Build a Lunar Colony (Photos)]

Musk and SpaceX are working to make the latter part of that vision a reality within the next 50 years or so. Last September, at the International Astronautical Congress (IAC) meeting in Mexico, the entrepreneur unveiled plans for a reusable rocket-spaceship combo called the Interplanetary Transport System. The ITS would help colonize Mars and, potentially, allow humanity to explore more distant worlds, such as the Jupiter moon Europa and the Saturn satellite Enceladus.

Musk has been relatively quiet about the ITS since then, but he said he plans to give an update about the architecture at the next IAC conference, which will be held this September in Adelaide, Australia. And he teased an ITS tweak that SpaceX has been working on.