After all, it has been almost 30 years since NASA last launched a spacecraft toward a completely unexplored planet.

NPR: NASA Sends Spacecraft to Pluto

The article 'Trekking the unexplored mountains of Morocco' was published in partnership with Lonely Planet.

BBC: Trekking the unexplored mountains of Morocco

But firms that make their money mining this planet say the Earth is one big, practically inexhaustible mine, with just as many unexplored corners as outer space.

WSJ: Exhausting the Earth's Resources? Not So Fast