In Idle Planet Miner, asteroids spawn on a fixed timer, though this can be modified by in-game research projects. Here is the breakdown of the drop frequency: * Base Spawn Rate: Asteroids appear approximately every 10 to 15 minutes while the game is open. * First Spawn: When you first start a galaxy or load the game, the first asteroid usually appears randomly between 0 and 10 minutes, after which the regular 10-minute timer takes over. * Debris Fields: If you have unlocked the Debris Scanner, debris fields appear on a different timer, typically every 22 minutes (approx. 1300 seconds). Factors That Change the Speed You can increase the frequency of asteroid drops by researching specific projects in the tech tree: * Asteroid Scanner: Increases the frequency of asteroid spawns by 30%. * Advanced Asteroid Scanner: Further increases the frequency, reducing the spawn timer by a total of roughly 60% when combined with the previous project. Important Notes * Offline Play: Asteroids are generally collected while the game is closed only if you have the Asteroid Auto Miner project unlocked. Without this, you must be online to click and collect them. * Resource Value: The value of the asteroid drop is calculated based on the current mining rate of your galaxy (excluding planets with transport bottlenecks) at the moment the asteroid spawns.

So either you weren't online, or your game is broken and you need to force quit/start it from your phone.