Asteroid mining may sound like science fiction. In fact, modern-day films like Alien and Moon and a myriad of books use interstellar mining as a background setting for their narratives. But this is no work of fiction.

More and more companies focusing on mining large asteroidal specimens, such as Planetary Resources and Deep Space Industries, have popped up recently. Their goal: to find cost-efficient ways to access the precious resources within these floating cash cows, whose yields are estimated in the trillions of dollars.

Asteroids, the rocky-metallic bodies left over from the formation of the solar system and still in the sun’s orbit, are replete with water, platinum, nickel and cobalt. While the benefits of mining scarce minerals like platinum are obvious, the water within asteroids can be broken down into hydrogen and oxygen for fuel and left in orbiting caches in space, solving one of the great problems of space exploration: fuel availability.

Accessing these floating deposits is another matter entirely. The three most logical options for mining involve bringing raw asteroidal material to Earth for use; processing the asteroids in space and bringing back only the desired materials; or transporting the asteroid into a safe orbit around the Moon, Earth or International Space Station.

And because not all asteroids are created equal, there’s the problem of determining which ones are even worth mining. Planetary Resources is attempting to solve this issue with space telescopes, small spacecraft (30 to 50 kilograms) that employ a laser-optical system that can be used to survey and examine near-Earth asteroids. The company placed a small version of the telescope aboard the Antares rocket on an unmanned mission in October 2014, but the rocket exploded just seconds after liftoff, destroying the cargo. Clearly, there is still a long way to go before asteroid mining is commonplace, but the first small steps are being taken now, and more likely than not they will end up being giant leaps forward.