A time to sow - Dayton Ward

Centuries ago a hardy band of survivors, fleeing a planetary catastrophe, took refuge in the inhospitable asteroid belt. Struggling for years to make what had once been short-term mining settlements into suitable colonies for permanent civilization, eventually they succeeded all too well, and their thriving population is approaching critical mass.
Now they must make a choice: to go on as they are on the crowded but functional asteroids or to give up all they have worked for in a desperate plan to rebuild their dead home planet. Their dilemma has brought them to the brink of civil war -- and into this volatile standoff comes the Enterprise, assigned a seemingly meaningless mission to chart this sector of space. Faced with an advanced society on the verge of self-destruction, it is up to the Enterprise, still carrying the weight of her demotion and disgrace, to find a way to lead the survivors to peace.