Abstract: Taking moon exploration as the research background, and wheeled mobile robots(WMRs) as the research object, this paper introduces the fault models and the sensor error models of mobile robots for deep space exploration in unknown environments. Some main features of the fault detection and diagonosis(FDD) and the fault tolerant control(FTC) for WMRs in unknown environments are analyzed. Based on these, some main approaches for FDD/FTC of WMRs, including multiple model based approach, particle filter based approach, sensor fusion based approach, layered fault tolerant architecture, and so on, are summarized. At last, the main challenges, difficulties and some future trends of this field are presented.