Global change has now become one of the most important problems for human kind. The major problems are global warming, stratospheric ozone depletion, tropical forest decrease, desertification, acid rain and decrease of bio-diversity. Among them, global warming and ozone depletion are the most urgent and critical problems for human beings. In order to solve these problems, accurate and comprehensive knowledge of the state of the art should be obtained. Polar orbiting earth observation satellite programs now being conducted under international coordination are programs aimed to solve these problems. They are composed of three kinds of series: i.e., ADEOS series by NASDA, Japan; EOS series by NASA, USA; and ENVISAT series by ESA, Europe. ADEOS is the first satellite of this series and will be launched by NASDA on August 1996. There are 8 sensors on-board ADEOS. They are provided by 6 agencies from 3 countries. The scientific objective of ADEOS is to contribute to the understanding of global environment, especially global warming and stratospheric ozone depletion.