Modify the planet's entity files in the GameInfo folder
planetResourceSetupInfo
asteroidSpawnAngleVariance 1.256637
totalMaxResourceAsteroids 4
metalResourceAsteroidSetup
minCount 2
maxCount 2
extractionRate 0.400000
refineryRate 0.060000
maxRefineryCount 6
crystalResourceAsteroidSetup
minCount 2
maxCount 2
extractionRate 0.400000
refineryRate 0.060000
maxRefineryCount 6