If the venerable television series "Star Trek" has taught us one thing, it's that the holodeck will never work properly and you should never go in there. But if it's taught us two things, the second must be that space is the final frontier. Even when we've managed to learn everything there is to know about Earth, there will still be mysteries to explore in space. Are there intelligent species living far beyond our solar system? What exactly is dark matter? Could wormholes hold the secret to faster-than-light travel?

The answers to these questions -- and others that we haven't thought of yet -- await us in space. But some people believe that groups of powerful individuals already know secrets about space the rest of us don't. Here we enter the realm of conspiracy theories. These theories range from educated guesses to wild speculation. Some also feature a cast of colorful characters, including secret governments and hyperintelligent alien species.

Keeping in mind that the truth is out there -- the guiding principle of another science-fiction television series -- we'll explore 10 of these space conspiracy theories. Prepare yourself, for once you learn, you can't unlearn. Let's begin.

­