Asteroids are space rocks orbiting our sun that don't quite make the grade as planets. There are millions of them in the solar system, most of which make up the asteroid belt, a zone between the orbits of Mars and Jupiter.

To the uninitiated, asteroids might not seem that interesting. They're inhospitable, irregularly shaped, small. But it turns out that these space slabs amount to much more than mere interplanetary rubble. They're chock-full of raw materials, and researchers are already envisioning a future where asteroids might be transformed into the Space Age equivalent of gas stations.

For instance, researchers Angel Abbud-Madrid and Christopher Dreyer of the Colorado School of Mines were recently given grants by NASA to develop a technique called optical mining, which involves using focused sunlight to leach asteroids of water and other useful chemicals, reports Colorado Public Radio.

"Think about this like gas stations in space," explained Abbud-Madrid. "You can have an infrastructure of fuel depots or gas station so that those can serve to fuel spacecraft that are moving in the neighborhood of Earth."

In other words, asteroids can serve as pit stops for long distance space travelers who need to restock. Collecting materials in space is also a more efficient way to travel than having to stock a spacecraft with everything it needs from home.

Here's how Abbud-Madrid and Dreyer's technique works: First, a spacecraft would inflate a bag around an asteroid. Then sunlight would be focused like a laser at the asteroid to drive out all the water and other chemicals in the form of vapor. Once isolated, this vapor will again be condensed and captured in another bag. This new rock of frozen raw materials can then be towed around and used as needed.

NASA's interest in the technique signals that space mining could become the next stage in space colonization. It's a necessary stepping stone before true interplanetary travel can be realized, kind of like how our highways required regular gas stations to be built before cars could travel along their length.

But the project is still in the early stages, so don't book your interplanetary ticket just yet. Besides, if you think gas is expensive here on Earth...