More than 100 spacecrafts have attempted to softly land on the surface of planet such as a moon, Mars, Venus, a comet and an asteroid in the history of space development. Although the landing success rate is approximately 40 percent, there are few failures caused by unexpected environmental influences and large deviations from the supposed environmental conditions. It is considered that this is due to conducting adequate investigation of environment around the exploration area by remote sensing and steadily progressing the mission while obtained Lessons Learned through a series of project. For this article, we first discuss about the space environment in which the planetary explorer works. Then, we outline how we verify and evaluate the specifications of components and system of the spacecraft with the tests partially simulating harsh environments such as heat, radiation and regolith. Furthermore, countermeasures against the harsh environments where the actuator and absolute angle sensor are exposed are also mentioned.