Attitude Maneuvers of a Rigid Spacecraft in a Circular Orbit
  A global model is presented that can be used to study attitude maneuvers of a rigid spacecraft in a circular orbit about a large central body. The model includes gravity gradient effects that arise from the non-uniform gravity field and characterizes the spacecraft attitude with respect to the uniformly rotating local vertical local horizontal coordinate frame. An accurate computational approach for solving a nonlinear boundary value problem is proposed, assuming that control torque impulses can be applied at initiation and at termination of the maneuver. If the terminal attitude condition is relaxed, then an accurate computational approach for solving the minimal impulse optimal control problem is presented. Since the attitude is represented by a rotation matrix, this approach avoids any singularity or ambiguity arising from other attitude representations such as Euler angles or quaternions. 
Taeyoung Lee, Melvin Leok, N. Harris McClamroch