It might surprise you to know that legendary science fiction and fantasy writer Ray Bradbury (search), who wrote about traveling to Mars decades before NASA's Spirit rover got there in the past year, thinks you're an alien.

Don't worry. The rest of us are too, according to Bradbury, who spoke to FOX News' Neil Cavuto on "Your World" Tuesday. In other words, we'll be the foreign beings exploring and eventually settling on other, untamed planets, just like we did here on Earth.

"We're the alien life," Bradbury, now 84, told FOX News. "Mars is empty. It's only waiting for us — it's a threshold for future generations. The future is vast, and we will become the Martians."

Bradbury thinks the dwindling interest in space travel needs to be rejuvenated by sending astronauts back to the moon.

"We should never have left the moon," he said. "We should go back now. It should be the base for going back to Mars."

Bradbury said man's first landing on the moon's surface was magical, an event that united the planet.

"The most wonderful night was the night we landed on the moon," Bradbury said. "The whole world celebrated. We were doing something for the world — something peaceful. Instead of destroying, we were building."

Cavuto asked Bradbury to respond to criticism that space travel is too expensive an endeavor to pursue, especially in an age plagued by terrorism.

"Well we're spending a billion dollars a day on armaments," Bradbury replied, referring to the U.S.-led war in Iraq. "All we'd have to do is take that billion a day from armaments and build rockets. Armaments do nothing for the future -- they protect us, yes, but we have to have more than protection. We have to have hope for the future. Space travel is the answer to that."

Earlier this year, FOXNews.com interviewed Bradbury shortly after NASA's six-wheeled robot, the Spirit rover (search), landed on Mars and snapped breathtaking photographs of the barren Red Planet.

• Interactive: Ray Bradbury, In His Own Words

Asked about his reaction to the rover's images of the Red Planet, Bradbury said: "Well, the 12-year-old boy in me jumped up and down and yelled. That's how I felt."

He told FOXNews.com that he'd been dreaming of traveling to Mars since he was 8, and predicted humans would live there someday, with the first ones going up about 50 years from now.

"We're going to become the Martians when we land there," he said. "When we explore and build communities, we become the Martians. That's a wonderful destiny for all of us ... Mars is empty now. Five hundred years from now, it'll be full of people."

But Bradbury is frustrated with the current progress of the U.S. space program, saying it's been flagging for years after a tremendous period of growth.

"We've let too much time go by," he told FOXNews.com. "We've been busy with war instead of being busy with peace. And that's what space travel is all about. It's all about peace and exploration and wonder and beauty."

Bradbury said on "Your World" that more international competition in space travel could help rekindle interest in our program in the United States. No matter how it happens, he wants it to become a priority again because he believes traveling to other planets will help perpetuate the human race.

"This will guarantee the immortality of mankind," he told FOX News Tuesday.

Bradbury has been one of the most influential, prolific and respected contemporary writers of science fiction and fantasy. In addition to "The Martian Chronicles" (search), published in 1950, Bradbury has written more than 500 creative works, including the novels "Fahrenheit 451" (1953) and "Something Wicked This Way Comes" (1962), along with hundreds of short stories, among them "Zero Hour" (1947) and "Rocket Summer" (1950). Many of his tales have been turned into films.

His newest book is titled "Bradbury Stories," a collection of 100 short stories written over 60 years.