Steve Boxall / X Prize Foundation

"Avatar" director James Cameron and friends enjoy a zero-gravity airplane flight last October. From left are Rob McEwen, chairman of US Gold; Cameron; Peter Diamandis, chairman and CEO of the X Prize Foundation; Elon Musk, chairman and CEO of SpaceX; and Jim Gianopulos, chairman and CEO of Fox Filmed Entertainment.

The director of the biggest blockbuster movie in history, James Cameron, still has his heart set on flying in space someday — and some reports suggest he might be up for a trip on the moon.

But Cameron says his trip into Earth orbit or beyond won't be merely a joyride: It's got to have a bigger purpose, and part of that purpose would be to document the real-life wonders of the cosmos on film, much as he did in the fictional, computer-augmented setting of "Avatar."

Cameron's spaceflight aspirations go back more than a decade: In the year 2000, reports emerged that he had gone through medical exams in preparation for a flight to Russia's Mir space station or the International Space Station. "We were putting together a 'filming mission,' a commercial space venture utilizing the capability of the Russian space system to get me up there with a camera," Cameron told me three years later.

Mir's demise in 2001 and the Columbia tragedy in 2003 closed off that opportunity, but in recent years Space Adventures, the Virginia-based company that has arranged every privately paid-for trip to the International Space Station, has been talking about selling a couple of seats on a beefed-up Soyuz spacecraft that would take a whirl around the moon and back. Such a flight could be accomplished by 2015, the company says, with seats going for as much as $150 million each.

Space Adventures says one high-profile client has already made a reservation. And although the identity of that client is a closely held secret, The Sunday Times of London reports that Cameron is "the name said to be in the frame."

The Times quotes unnamed associates of Cameron as saying he's been talking with NASA as well as the Russian space agency about mounting a 3-D camera on the space station to shoot a documentary patterned after "Aliens of the Deep," Cameron's film about the deep ocean. "The technology is very similar, and Jim is fascinated by outer space," one source told the Times. "But the cameras have to be made a lot lighter than current models."

Based on what Cameron told me last Friday, at the opening of an "Avatar" exhibition at Seattle's EMP museum, a film documenting the director's trip to the space station and around the moon just might be a project big enough to justify the big expense. If the project were to bring in even a tenth of the $2.8 billion gross reported for "Avatar" to date, it'd be an attractive venture on financial as well as inspirational grounds.

Cameron didn't spill any secrets during my quick "blue-carpet" interview — either about future spaceflights or about the upcoming "Avatar" sequels, due for release in 2014 and 2015. But the timing of "Avatar 2" and "Avatar 3" suggests that the director's calendar will be a lot clearer after 2015, just in time for that trip around the moon.

This edited transcript of our Q&A gives you an idea where Cameron's head is at when it comes to outer space:

Cosmic Log: Have you learned anything from planetary science in the past couple of years that might show up in the "Avatar" sequels?

James Cameron: "I stay up with that all the time — and, yeah, we're always finding new stuff. It may not show up necessarily as a plot point, but it may show up in the background of a shot. For example, a polar aurora on a gas giant, or something like that, similar to what was observed at Saturn."

Q: Do you still want to go into space someday?

A: "I would if there was the right opportunity and the right reason. For me, the right reason is not just to sorta go up and do a few orbits and come back down and tell all my friends about it. It would be to make some kind of a film, especially in 3-D, that has an important message for some people. Ten years ago, I wanted to do that, but the message was that we needed to do long-duration spaceflight with the space station as a steppingstone to going to Mars. Now, of course, all the funding's gone from the Mars program, so it's kind of pointless to get people keyed up for something that's not going to happen. I'd have to find a reason, more than just being a tourist."

Q: Do you keep in touch with Elon Musk [the millionaire founder of the SpaceX rocket venture, who has aspirations of going to Mars in as little as 10 years]?

A: "Oh, yeah. Elon is making very strong strides. I think he's the likeliest person to step into the shoes of the shuttle program and actually provide human access to low Earth orbit. So ... go, Elon!"

Q: You might be going up on a SpaceX Falcon rocket one of these days...

A: "Yeah, well, sure, the Dragon capsule has already orbited. It's a seven-person vehicle that's already orbited and been recovered safely. Obviously they didn't have people in it for that test flight. The funny thing is, so much was made of SpaceShipOne and all that, and that was great. But in comparison to orbiting a manned vehicle and bringing it back safely, and doing it privately? That's big. But hey, it didn't really get headlines. I don't understand that.

"It wasn't an X Prize. It wasn't a race. SpaceX did it, and didn't make a big deal out of it."

Space Adventures' Eric Anderson said last month that the unnamed client for the round-the-moon mission is planning a project "that is going to address an issue and a concept that is of great importance to the world."

"It will be something that captivates a lot of people," he said. "I really do look forward to our ability to announce that."

I'm looking forward to it as well. But if I had to bet today on what the mission is, and who's going to be on it, I'm totally betting on James Cameron with a 3-D camera.

More about James Cameron's adventures:

• Cameron's 3-D camera misses out on Mars flight
• 'Avatar' director stars in NASA videos
• Relaunch of 'Titanic' in 3-D tied to tragedy's anniversary
• 'Avatar' gets top billing at Seattle museum

Come back to Cosmic Log later this week for a preview of future filmmaking from the special-effects wizards of "Avatar."

You can connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. Also, give a look to "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.