During extraterrestrial planetary exploration programs, autonomous robots are deployed using a separate immovable lander and a rover. This mode has some limitations. In this paper, a concept of a novel legged robot with one passive limb and singularity property is introduced that has inbuilt features of a lander and a rover. Currently, studies have focused primarily on a performance analysis of the lander without a walking function. However, a systematic type synthesis of the legged mobile lander has not been studied. In this study, a new approach to the type synthesis used for the robot is proposed based on the Lie group theory. The overall concept and design procedures are proposed and described. The motion requirements of the robot and its legs, which are corresponding to the multi-function, are extracted and described. The layouts of the subgroups or submanifolds of the limbs are determined. The structures of the passive and actuated limbs are synthesized. Numerous structures of the legs with a passive limb are produced and listed corresponding to the desired displacement manifolds. Numerous novel structures of legs for the legged mobile lander are presented and listed. Then, four qualitative criteria or indexes are introduced. Based on the proposed criteria, a leg's configuration is selected as the best. A typical structure of the legged mobile lander is obtained by assembling the structures of the proposed legs. Finally, the typical robot is used as an example to verify the capabilities of the novel robot using a software simulation (ADAMS).