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Whether it’s colonizing Mars or harvesting materials from asteroids, the future of space travel is all about embracing the cosmos as a frontier for human expansion—and also profit.

Watch the video above to see how two US companies, Planetary Resources and Deep Space Industries, plan to mine asteroids within the next few decades. If their mission sounds familiar, it’s because it’s been a recurring plot line of sci-fi movies for decades, from Avatar to Armageddon.

But this is no romantic quest to the far reaches of space. Ultimately, the question for these companies is less whether they can mine asteroids, and more whether they can make money doing it.

“This isn’t the 24th century in Star Trek, and it’s not the fantasyland of Star Wars,” Planetary Resources CEO Chris Lewicki told Quartz. “We’re going to view the process of developing resources and mining asteroids with a lot of the same business principles, a lot of the same financial instruments and with a lot of the same investment dynamic and risk tolerance that we see… drilling an oil well.”

Asteroids are essentially floating hunks of rock that often contain resources like frozen water. If mining companies can figure out how to extract and store the water in space, they could potentially provide a more economic way for future travelers to refuel their spacecraft—by converting the water to charged ions or by running on steam power. The water could also be used for habitats or colonies. At least, that’s the theory.

The sums of money involved are huge. Take NASA’s asteroid missions. It’s about to launch its billion-dollar OSIRIS-REx mission, and will wait seven years for it to return a 60-gram asteroid sample. Its Asteroid Redirect Mission slated for the 2020s will move a large chunk of an asteroid into lunar orbit, and is projected to cost $1.25 billion.

But private companies have beaten NASA on costs before. For example, SpaceX has already made it much cheaper to ship materials into space. Currently, for a flight to low Earth orbit on its Falcon 9, SpaceX charges $62 million. And both asteroid mining companies are betting that they can mine asteroids much more economically.

First, though, they must prove their technology.

“While it doesn’t on the face of it look like everything could fall into place, it looks like it’d be too much of a capital expenditure, the fact is that this economy is being built on the back of a profitable business plan in the short-term,” Daniel Faber, CEO of Deep Space Industries, told Quartz. “And in the medium term, in the 10-15 year timeframe, it’s completely viable.”