Energy harvesting in space is the fundamental requirement in almost all space exploring systems and applications. Environmental radiation, such as solar and Albedo radiation, in space and generation of thermal load during operation tends the flow of heat inside the satellite structure. Thermal load is driven by subsystems and electronics. For this purpose, we use thermoelectric module to produce energy from waste heat as well as control temperature of the system. Thermoelectric devices are widely used in different space applications and Radioisotopic thermoelectric generator are widely used different space missions. In this paper comprehensive discussion has been done on recently proposed alternative designs, material competency and life-scaling models for improving longevity of the thermoelectric modules for space applications. A precise discussion has been drawn on space devices and their obstacles. As part of deep space mission, to ensure the longevity of device, work is being done on mechanical stability and suppression of sublimation. © 2020, Univelt Inc. All rights reserved.