<p>The 6DOF coupled control for spatial proximity operation is the critical technique for the observer spacecraft to take the monitoring and spotting mission. In order to solve the 6DOF coupled effect issue in translation and rotation control for spacecraft, adapt the dual quaternion framework is elegant and integrated. However, adapting with this model, the estimation of the dual inertial matrix cannot be directly constructed. In this article, a direct method is devised to create the estimation of dual inertial matrix derivative by extending the dual quaternion to diagonal matrix and compositing with an antisymmetric identity matrix. An adaptive sliding mode control technique is developed based on this efficient parameter estimation algorithm that can compensate the uncertainties of the inertia parameters. The Lyapunov stability is proved that the controller is asymptotically stable. The convergence analysis is done accordingly to prove faster convergence. Finally, the comparison results are shown in the simulation that the better performance than some advanced sliding mode controllers. Overall convergence performance is compared with advanced adaptive fast terminal sliding mode control and adaptive high order super twist sliding mode control.</p>