Disable star ratings for nonmembers

is there a way to disable the ability to rate a listing unless you are a member and signed in? Currently anyone can rate a listing. My listings are going to be a service based listing . so the current star rating system is ineffective as it allows the possibilty of someone just sitting on a rating and stacking em up. I had to disable it as it serves no use .. Though I would love to be able to use it