Alex, has that intraversible function been added yet? That could really come in handy for event orriented levels. You could also use it for abilities, say there are asteroids 1,2,3 with one seedling on asteroid 1. When the seedling is on #1, you could have an ability that allows you to put down a laser mine when you select an asteroid and right click in space. The cooldown for this could be as such: when you move the seedling to the corresponding asteroid, it could start growing a defense tree, and when it hits the right level, you can use the ability again, for longer cooldown timers, a second or third defense tree could start after the first has reached it's max level.
Also, I was thinking that a function to make asteroids invisible might be nice (I don't think one exists) that makes it so that the empire cannot even tell the that asteroid is there, whereas when a roid is hidden, it just says it is undiscovered, if it is invisibible, it wouldn't even show up on the map. I suppose this could be done by adding and removing roids in the game, but having a function might be more convenient. Just kidding, you already have this one
And finally, can you allow it so that asteroids do not all have to link up? like say 2 asteroids are linked, but are disconected from the rest of the secter? I tried to make a level like that and it refused to load.