A spherical modular autonomous robotic traveler (SMART) is provided for delivering a payload along a surface from a first position to a second position. The SMART includes an outer spherical shell for rolling along the surface, an inner spherical chamber within the outer shell to carry the payload, a plurality of weight-shifters arranged in the inner chamber, and a controller to activate a select weight-shifter among the plurality. The weight-shifters can be arranged symmetrically or asymmetrically. The outer shell rolls in a direction that corresponds to the activated weight-shifter by torque induced thereby. The inner chamber maintains its orientation relative to the surface, even while the outer shell rolls along the surface. Each weight-shifter includes a channel containing an armature and an electromagnet activated by the controller. For the symmetrical arrangement, the channel is oriented from bottom periphery to lateral radial periphery of the inner chamber. The electromagnet is disposed proximal to the channel at the lateral radial periphery. The armature travels from the bottom periphery within the channel to the lateral radial periphery upon activation of the electromagnet.