Asteroid
An Asteroid is a small, immobile, natural mass of stone voxels in the game's space environment. They typically occur in clusters and despite their variety of sizes, they are too small to exert any natural gravity on grids or players.
Gallery
A generic asteroid
An example of an asteroid base from the Sparks of the Future scenario
Tiny static asteroid rocks pose a danger to fast flying ships
Resources
In addition to ubiquitous stone, some asteroids contain lucrative deep veins of Ores that you can mine with drills. In unmodded games ("vanilla"), they can contain all types of ore that are available in the game. Each asteroid may contain two or more types of ore, with ice also counted as an "ore". Pure ice asteroids exist but are very rare. Especially Uranium Ore is found only in asteroids and very valuable.
How to change asteroid density
Worlds in Space Engineers are infinite and filled with procedurally-generated[1] asteroid clusters as needed.
You can adjust the asteroid amount in the World Settings but only before you start the game for the first time. You can choose between high and low density; the default setting is called "normal density".
How do asteroids spawn
Asteroids only spawn when players are near, this means that an exploration drone cannot trigger their generation.
When you travel far away from an asteroid, it will despawn to save resources. When you move back into its location, it will regenerate exactly the same way it did the first time, and the same location.
Important: Once you damage an asteroid in one way or another, it becomes a persistent element and takes up resources permanently. Something to be aware of if you are having performance problems.
Asteroids are procedurally generated: Mathematical algorithms based on a seeded random value mixes asteroid prefabs together in various way to create asteroids that looks interesting and more or less unique. Ores are selected the same way.
A seeded random is a method of creating results that look random but are actually predictable if the same starting "seed" value is used. This allows the game to regenerate the same asteroid layout each time, ensuring consistency while still creating variety.
Building on asteroids
In Survival Mode, asteroids are a relatively protected place where you can build space bases, either inside of, or attached to, the asteroid’s voxels. For related options, see also "Unsupported Stations" in the World Settings.
In Creative Mode, you can shape and edit asteroids and the ores on them (other than by drilling), for details, see Voxel Hands. You can add asteroids yourself, for example when creating a custom scenario; just use the same method as for How to Spawn Planets and Moons Manually, but select Asteroids instead. Then paint ore materials on them using Voxel hands.