Even in this age of free-flying conspiracy theories, this one's a doozy.

On Thursday (June 29), a guest on Alex Jones' radio show named Robert David Steele claimed that Mars is inhabited — by people sent to the Red Planet against their will.

"We actually believe that there is a colony on Mars that is populated by children who were kidnapped and sent into space on a 20-year ride, so that once they get to Mars, they have no alternative but to be slaves on the Mars colony," Steele told Jones, the founder of the controversial InfoWars website. [25 Space Conspiracies That Just Won't Die]

It's unclear why this "ride" would last two decades; it takes just 6 to 9 months to reach Mars using current propulsion technology. Perhaps Steele believes that the kidnapped children return to Earth, as adults, 20 years after being spirited away?

Whatever the details may be, Jones seemed open to the possibility.

"Look, I know that 90 percent of the NASA missions are secret, and I've been told by high-level NASA engineers that you have no idea," Jones told Steele, who the show billed as a "CIA insider." "There is so much stuff going on."

Jones went on to add that "clearly, they don’t want us looking into what is happening; every time probes go over, they turn them off."

The Daily Beast did some due diligence on Steele's assertion, contacting NASA for a comment.

"There are no humans on Mars. There are active rovers on Mars. There was a rumor going around last week that there weren’t. There are," Guy Webster, a spokesman at NASA's Jet Propulsion Laboratory in Pasadena, California, who specializes in the agency's Mars-exploration activities, told The Daily Beast. "But there are no humans."

Alex Jones has supported and promulgated conspiracy theories in the past. He has claimed, for example, that the December 2012 massacre in Newtown, Connecticut — in which 20-year-old Adam Lanza shot and killed 27 people, including 20 first-graders — was a hoax.

Mars has proven to be fertile ground for conspiracy theorists over the years as well. There's the famous "face on Mars," of course. And more recently, UFO enthusiasts have claimed that NASA's Curiosity rover has captured images of a variety of Red Planet animals that resemble rats, lizards, squirrels and crabs.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.