Josh Gates is back with “Expedition Unknown,” and this time he’s seeking answers to the oldest questions on earth: Are we alone? Are there other intelligent beings in outer space? Have they visited our planet?

“This is a big question… are we alone in the universe? It’s kind of man’s eternal question,” said Gates, whose four-part investigation, “Expedition Unknown: Hunt for Extraterrestrials,” premieres Oct. 4 on the Travel Channel.

“I really wanted to tackle this question. What is fact? What is fiction? What is really out there? We took on a huge expedition to go around the world and really investigate this story from a lot of different angles….

“It is a journey that took us about 50,000 miles around the planet to four different [countries],” he explained. “We really went as far as we could to meet the people that had something to say about this topic and to really meet with the best of the best — the most prominent scientists, the most compelling eyewitnesses.”

The adventurer/explorer credited the show for taking him to places most people can’t visit.

“We were given really extraordinary access to go behind the scenes at NASA and to understand their work in terms of this question and how they are studying the possibility of life out there in the universe….

“We went to some really remote places on this trip. Part of the show takes place on Easter Island, we descended down into some never-before-explored caves in Easter Island. We also went all the way to Zimbabwe to meet with eyewitnesses and to work with scientists who were trying to recover meteorites from an impact crater.”

Gates said he doesn’t consider himself a daredevil — “It’s funny,” he said. “I don't. It’s my job.” But he admitted he sometimes can’t believe the things he does.

“But then when I look at it later, certainly, sometimes I go ‘Wow.’ Sometimes I can’t believe I jumped out of that airplane. I think my mother certainly likes to remind me later that I do a lot of dangerous things.

“But really, I’m so fascinated by the stories we are investigating, and I am so thrilled to be able to go out and do these hands-on explorations, that in the moment it just feels exciting and fun.”