  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.
