The mission is the community's center of gravity. Members are attracted to the community by its vision for the future, its past accomplishments, and shared values. The mission's gravity is a function of how well members understand it and contribute.
In the Orbit Model, the mission is the community's center of gravity. The mission is what attracts new members and facilitates the development of love and reach. The mission is what members gravitate around. The deeper the tie to the mission, the closer the member will orbit.
The clearer that a community is about it's mission, the easier it will be for members to align themselves around it and develop love and reach. A community's mission can be as light as "enjoying our shared interest in old movies" or as ambitious as "giving everyone on planet earth access to clean drinking water".