Outer Planets Alliance

The Outer Planets Alliance, abbreviated OPA, is an organization that started its life as a labor union or advocacy group, fighting for the interests of inhabitants of the Belt, often in direct conflict with the inner planets' Earth Mars Coalition Navy. Its logo is a split circle and headquarters is located on Tycho Station.

The OPA is described as either a social movement, according to people sympathizing with Belters, or a terrorist network, according to the inner planets.