Micro-gravity and space environments pose novel questions for the design of robots and manipulators. On earth, robots are typically attached to the ground which provides a fixed support during movements. However, in space, there is no fixed ground and movements are specified by action-reaction principles. Motion planning of space robots is specially challenging due to absence of a fixed base. Our lab has developed novel motion planning methods that build upon the underlying dynamic equations of motion in the space. The methods were demonstrated using designs of free-floating planar robots on air bearings.