Rogue asteroids mechanic is not functioning

[Malxe]

The mechanic of having rogue asteroids spawn off-screen and fall into orbit in a solar system for several turns before crashing into a randomly selected planet does not appear to be functioning. They typically start to show up after a week or two of gameplay, if I recall correctly.

These objects are owned by a pseudo-player account called 'NATURE'. They behave like ships in that they fly to a solar system and settle into orbit for a number of ticks before colliding and acting like planetary bombardment. The asteroid object stats can be found in res/rules/standard/Astroid.xml