There’s gold in them thar’ space rocks, say the miners of the future. There’s also platinum, rare earth elements, and even water. Mining in space may sound like science fiction, but as the founders of two space mining companies recently told me, their plans are very real.

About 4 billion years ago, gravitational turmoil in the early Solar System bombarded the inner planets with asteroids. Astronomers call this period the Late Heavy Bombardment. Early Earth was a roiling mass of lava, and as metal-rich asteroids hit the molten surface, they sank inward to the planet’s core. That’s why Earth’s core is made of iron, and why metals like gold, silver, and platinum are relatively scarce in our planet’s crust.

“What we are mining on Earth really is mining the asteroids,” explains Naveen Jain, founder and executive chairman of Moon Express. On Earth today, he says, “the easy stuff has been mined, and now you have to continue digging deeper and deeper and deeper.” Indeed, what we aim to mine on asteroids isn’t so different from what we mine on Earth.

The asteroids still orbiting the Sun are made of the same materials as the ones that made up the Late Heavy Bombardment. Their highest concentration is in the Asteroid Belt, a band that lies between the orbits Mars and Jupiter, but there are plenty of asteroids whose orbits carry them much closer to Earth. Astronomers call them “near-Earth objects,” and Chris Lewicki, president and chief engineer of Planetary Resources, says they’re the best place to start space mining. Planetary Resources will test its Arkyd 3 prospecting satellite in orbit later this summer, and plans to start commercially mining asteroids by the early 2020s.

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