An apparatus and method of unified orbit and attitude control for acquisition and maintenance techniques of multiple satellites in a formation based on GPS input, utilizing Modern Feedback Control for providing precise autonomous on-board orbit and attitude control. This control system can place and maintain any satellite in its designated location in a formation, while simultaneously providing the capability to attain and maintain the attitude of any of the satellites in the formation with respect to the reference `head-of-fleet` satellite. Utilizing the two different options of GPS signal, code pseudo range for orbit determination and control and phase pseudorange for attitude determination and control, the relative orbit and attitude state vectors of all the satellites in the formation is determined and modern advanced multivariable feedback control techniques, for example, linear quadratic Gaussian/loop transfer recovery controllers for orbit control and Sliding Controller or Lyapunov Controller for attitude control are used to provide a unified orbit and attitude control. The control of acquisition and maintenance for multiple spacecraft formation flying is a tracking problem, which can be converted into a regulator problem using the relative orbit and relative attitude kinematics and dynamics.