Asteroids

Asteroids (biome) are the most common biome in the Space layer of planets. They have ore (sometimes of a higher tier than the planet itself, e.g. Tungsten Ore on tier 1 planets), including Diamonds.

You can easily reach Asteroids in your mech (by activating its flight mode).

They are not to be confused with Asteroid Belts, which are a special type of a world.