In this paper we present a 6 degrees of freedom (6-DOF) synchronization scheme for a deep space formation of spacecraft. In the design, which is referred to as a mutual synchronization scheme, feedback interconnections are designed in such a way that the spacecraft track a time varying reference trajectory while at the same time keep a prescribed relative attitude and position. The closed-loop system is proven uniformly locally asymptotically stable, with an area of attraction which covers the complete state-space, except when the spacecraft attains an attitude where the inverse kinematics are undefined. The proof is carried out using Matrosov's Theorem.