Path planning for satellite slew maneuvers is considered as an optimal control problem. The goal is to design rapid maneuvers with vibrational modes resting time as short as possible in order to provide more time for space imagery. In this paper, this optimal time and control effort problem is addressed using differential flatness and Bspline collocation. The flatness allows for reformulating the original optimal control problem as a tractable geometric programming problem with no numerical integration, and with a minimal number of decision variables. A direct consequence of flatness is that the transformed constraints describe generally a non convex subspace. In the proposed approach, a flat suboptimal convex problem is derived by means of off-line convex approximations of the feasible space and a measure of its conservatism is given. Numerical results are discussed and compared to the results generated from an in-service industrial path planner available at French Space Agency, CNES.