The billionaire founder of the SpaceX rocket venture, Elon Musk, says that within five years he wants to make orbital space trips available to regular passengers — including himself. And if he sticks to his timeline, Musk just might go beyond Earth orbit before NASA's Orion spaceships do.

"Am hoping to travel to orbit in about 5 years, beyond in 7 to 10," he wrote during a Twitter chat organized by The Associated Press. Later, he said it would be "5 years max before we fly civilians." That suggests that Musk is aiming to take an orbital trip in 2017 or so, along with paying passengers, and follow that up with more ambitious journey beyond Earth orbit in the 2019-2022 time frame.

In comparison, NASA's current schedule calls for astronauts to launch aboard its Orion multipurpose crew vehicle, the first NASA spacecraft since the Apollo era capable of taking a crew beyond Earth orbit, no earlier than 2021. The space agency is targeting its first manned mission to a near-Earth asteroid in the mid-2020s.

There are a few caveats to Musk's prediction. First of all, rocketry feats tend to take longer than Musk expects, as he himself acknowledged a couple of years ago during an interview. There's no better illustration of that than the buildup to SpaceX's history-making commercial cargo mission to the International Space Station, which has been delayed repeatedly over the past few months. The launch of SpaceX's Dragon capsule atop a Falcon 9 rocket at Cape Canaveral Air Force Station in Florida had been set for May 7, but SpaceX said liftoff would be held up while NASA was double-checking changes in the flight software.

Musk said today that he was "not surprised" by the latest holdup.

"This mission is super complicated, so delays are to be expected," he wrote during the chat. He said a new launch date would be selected in the "next few days."

This SpaceX mission is a test run, and it's not certain whether the Dragon will get all the way to its docking port on the space station's Harmony module this time around. If it does, that would clear the way for SpaceX to begin robotic cargo resupply missions in earnest later this year, under the terms of a multiyear $1.6 billion contract with NASA.

Musk, who plowed $100 million of his own dot-com fortune into SpaceX, is essential to the venture's success. He's not only the chief executive officer, he's also the company's chief designer and the chief engineer for the Falcon 9 and the Dragon. What's more, he's the CEO and product architect for Tesla Motors, an electric-car pioneer; and the non-executive chairman of SolarCity, a solar-panel company that's reportedly getting ready for an initial public offering.

His key role in so many ventures raises another caveat about that future space trip. Would Musk's investors let him go? On that score, the scenario could well play out the way it did in "The Man Who Sold the Moon," a novella by one of Musk's favorite authors, Robert Heinlein. The story focused on a tycoon who creates a wildly successful lunar venture — but whose dream to travel to the moon himself is frustrated by the venture's majority owners. They decide his blastoff would pose too much of a risk to their fortunes.

Speaking of Heinlein, Musk said during today's chat that "The Moon Is a Harsh Mistress," one of the sci-fi author's classics, ranks as a favorite book. The other books on top of Musk's reading list include "Ignition!" by John Clark, "Foundation" by Isaac Asimov and "Modern Engineering for Design of Liquid Propellant Rocket Engines" by Dieter Huzel and David Huang.

Musk also hit on the long-running theme that has motivated his rocket interest for more than a decade: making humanity into a multiplanet species. When asked what regular people could do to support SpaceX's efforts, Musk replied: "Rally people around the idea of making life multiplanetary with a base on Mars."

In past interviews, Musk has said it'd be possible for SpaceX to send humans to Mars in 10 to 20 years, and he truly believes that's the only way to ensure the species' long-term cosmic survival amid out-of-the-blue threats such as asteroid strikes.

"For humanity to have an exciting and inspiring future, we cannot be confined to Earth forever," Musk wrote. He said he was "highly confident that Mars can be self-sustaining without terraforming."

He returned to that theme in a video spot airing tonight on PBS' "NewsHour" program. "I'm talking about sending ultimately tens of thousands, eventually millions of people to Mars, and then going out there and exploring the stars," he said.

Does Musk have his head in the clouds? Or is it possible that the 40-year-old billionaire is on to something? Feel free to weigh in with your comments below.

More about SpaceX and Elon Musk:

• Next steps in the new space race
• Elon Musk says it'd be 'cool' to fly in space
• SpaceX has a lofty goal: Help save humanity
• CNBC: Elon Musk on why SpaceX has the Right Stuff
• Cosmic Log archive on the new space race

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.