Asteroid mining is another one of those ways to earn money, and it turns out to be a pretty good gig. Once you buy the mining laser, all you have to do is scan a nearby asteroid to begin mining. It turns out to be pretty profitable, especially early on in the game.
All of the asteroids yield one of the types of ore: titanium, silicon, iron, tungsten, and others. Obviously, the more valuable ores are harder to find, so there is reward in going to the far reaches of the system in search of precious commodities.