well i maybe got a idea.
you make some tool the player can dump out of its spacecraft when he/she is in sollarsystem vieuw. This device wil start gathering junk out of space and in time create a complete new planet in the system.
ofcource you have to make a max alowed amount of planets per solarsystem
The device need to be expansive and the collor of spice need to be selected by the computer randomly.
ow and maybe more diferent collors of spice woud be nice
like white, black, brown