Custom Asteroids

Lets users control where asteroids appear

License: MIT

Game Version: 1.12.4

Downloads: 50,617

Author: Starstrider42

Mod Website: Forum Thread

Followers: 103

Outdated Mod

This mod is not known to work with the latest version of Kerbal Space Program. Proceed with caution.

Information Changelog Stats

Custom Asteroids is a mod for Kerbal Space Program that expands the stock asteroid functionality to enable more realistic (or less realistic) asteroids. It is designed to be easily and naturally extended by players. API documentation is available at

Custom Asteroids preserves the basic mechanics of Kerbal Space Program, in that asteroids must first be discovered, then tracked to give them a known orbit. However, under Custom Asteroids most asteroids will not be on a flyby course for Kerbin. Instead, the mod places asteroids in specific populations throughout the stock solar system. Additional populations, such as belts suitable for mods such as Real Solar System or Alternis Kerbol, may be added by third parties.

To use Custom Asteroids, install the mod in your GameData directory. New asteroids in both new and old save games will immediately be generated according to the new rules. Asteroids already created, including untracked asteroids, will not be affected. There is no in-game interface; Custom Asteroids works entirely in the background. Several options may be set in a separate file.

Version v1.9.0 for Kerbal Space Program 1.12.4

Released on 2021-01-24

This release of Custom Asteroids works with KSP 1.10 and later.

New Features

  • Asteroid groups can now create comets that behave according to stock rules (e.g., orbit-dependent science classes).


  • The CaCometActive part and cometSample experiment are now deprecated; use PotatoComet instead. They will be removed in version 2.0.0.
  • Stockalike.cfg now emulates the four stock comet classes. Comets have been removed from Basic Asteroids.cfg and Trans-Jool.cfg.
  • Added a "Main Belt Comet" comet class.
  • Nerfed spawn rates of Drestroids and Jool Trojans.
  • Modernized Kuper belt objects and made them more realistic.
  • Restricted Kuper belt detections to large objects.

Bug Fixes

  • New asteroids/comets now trigger the corresponding game events.
  • Scene changes no longer cause duplicate asteroids.

Download (123.56 KiB)

Version v1.8.0 for Kerbal Space Program 1.9.1

Released on 2020-07-19

This release of Custom Asteroids works with KSP 1.4 through 1.9.

New Features

  • Asteroid groups can now have custom size distributions. They are still limited to the asteroid sizes provided by the stock game.

Bug Fixes

  • Loading a KSP game in which many years have passed no longer causes Custom Asteroids to "churn" through redundant asteroids.
  • Resource drills now work when Custom Asteroids is installed but Community Resource Pack is not.
  • Asteroid configs consisting entirely of limited-number or conditionally-spawned asteroids no longer emit error messages.
  • Asteroid configs consisting entirely of limited-number or conditionally-spawned asteroids no longer cause the spawner to get stuck in a zero-asteroid state.

Download (116.83 KiB)

Version v1.7.0 for Kerbal Space Program 1.9.1

Released on 2019-05-13

This release of Custom Asteroids works with KSP 1.4 and later.

New Features

  • Asteroid groups can now have limits on the number of asteroids that spawn at once.

Bug Fixes

  • Solar day (<planet>.psol in configs) is now correctly calculated for bodies other than Kerbin.

Download (110.98 KiB)

Version v1.6.0 for Kerbal Space Program 1.7.0

Released on 2019-01-21

This release of Custom Asteroids adds localization support and fixes several bugs. It works with KSP 1.4 and later.

New Features

  • Custom Asteroids is fully localizable.
  • Asteroid group titles can now use the string "<<1>>" to say where the asteroid ID should go. Names without this string will continue to use the old behavior (where the title is a prefix for the asteroid ID).

Bug Fixes

  • Intercept orbits that enter the target planet's SOI at very low speeds are now handled correctly.
  • Identical asteroids are much less likely to appear in the same game.
  • Asteroids renamed through the right-click menu will no longer be deleted.

Download (103.18 KiB)

Version v1.5.0 for Kerbal Space Program 1.6.0

Released on 2017-05-29

This release allows Custom Asteroids to work with KSP 1.3, and adds some minor improvements. This version ignores the new Sentinel telescope; support for it will be added in a later version.


  • Support for KSP 1.3.
  • Silicates, Hydrates, Gypsum, ExoticMinerals, and RareMetals added to asteroid configs. Stony and carbonaceous asteroids now have Hydrates instead of Water.
  • Options format and file location have changed to let mods force options (e.g., asteroid lifetime) using ModuleManager. Old options files will be migrated automatically.
  • All stock configs now explicitly say which probability distributions they are using. This change is purely for self-documentation; the defaults for each orbital element are still the same.

Download (82.32 KiB)

Version v1.4.1 for Kerbal Space Program 1.2.2

Released on 2017-03-02

This version fixes a player feedback issue that was not addressed in the 1.4.0 release.

Bug Fixes

  • Exception messages are more specific about which config node is responsible for failures.

Download (81.49 KiB)

Version v1.4.0 for Kerbal Space Program 1.2.2

Released on 2017-02-20

This release is primarily a KSP 1.2 compatibility update. A few minor gameplay changes that were pushed before the KSP 1.2 release are also included.


  • Support for KSP 1.2.
  • Asteroid spawn rates have been roughly halved, so that there should be 10-15 asteroids if running for a long time without tracking.

Bug Fixes

  • EL compatibility patch no longer processes non-asteroid parts

Download (81.12 KiB)

Version v1.3.1 for Kerbal Space Program 1.1.3

Released on 2016-05-07

This version fixes some bugs and balance issues discovered after the release of Custom Asteroids 1.3.0.


  • Cleaner handling of PotatoRoid resources. Requires ModuleManager 2.6.23 or later.
  • Adjusted resource amounts to make asteroid types more distinct. Completely reworked Substrate and Karborundum resources based on better understanding.

Bug Fixes

  • CustomAsteroidPlanes blocks now work the same in all save games.
  • Asteroids will now spawn if Custom Barn Kit is installed.
  • The MetalOre resource is now properly handled.

Download (75.89 KiB)

Version v1.3.0 for Kerbal Space Program 1.1.2

Released on 2016-04-24

This version updates Custom Asteroids for KSP 1.1, and also adds many new features to the config format. Old config files will still work with the new release.

New Features

  • Support for KSP 1.1.
  • Limited support for custom asteroid types.
  • Can now customize asteroids on intercept trajectories.
  • Asteroids can now appear only under certain conditions.
  • Asteroid population blocks now support the log-normal, (rescaled) beta, and gamma distributions.
  • Asteroid .value syntax now supports several characteristic periods and speeds.
  • Asteroid orbits can now be given relative to an inclined plane. Useful for mods like RSS and Harder Solar System.


  • DEFAULT config blocks are now deprecated. They will be removed in version 2.0.0.
  • Stockalike asteroids have been split off into their own config file.
  • Some tweaks to asteroid spawn rates.

Bug Fixes

  • Invalid populations will no longer stop other populations from loading.
  • Near-Kerbin asteroids will no longer appear on unbound orbits, and are much less likely to appear in the main belt.
  • A large number of asteroids will no longer appear when the tracking station is upgraded while using the fixed-rate spawner.
  • Mean anomaly and mean longitude of celestial bodies are now calculated correctly.

Download (75.44 KiB)

Version v1.2.0 for Kerbal Space Program 1.0.5

Released on 2016-02-21

This version updates Custom Asteroids for KSP 1.0, and includes a number of stability improvements as well.

New Features

  • Support for KSP 1.0.
  • A prominent warning will now be displayed in-game if CustomAsteroids is installed without any asteroid configs.


  • Configs updated to reflect KSP 1.0 and popular solar system mods.
  • Logs now follow the standard convention (prefixed by "[CustomAsteroids]").
  • More consistent feedback for bad population definitions.
  • The setting "UseCustomSpawner" has been replaced by a more flexible setting, "Spawner". Old settings files are supported and will be migrated automatically.
  • The "Stock" value of "Spawner" will no longer use the KSP spawner, but an internal emulation. This change will make future improvements to the mod much easier to implement.
  • The previous public API has been marked as deprecated (though it is unlikely that anyone was using it, as it was never finished). It will be removed in version 2.0.0.

Bug Fixes

  • Asteroids will now be properly removed at very high (larger than 100,000×) time warps. Players may see substantial lag as the despawner works, however.
  • Asteroid groups using orbitPhase {epoch = GameStart} will now work correctly in RealSolarSystem.
  • Asteroids will now be randomized between different save games.
  • More graceful handling of invalid options files.

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