Abstract: A terrestrial environment observation satellite is provided, which can solve such environmental problems as earth temperature increase, ozone layer destruction and occurrence of abnormal weather occurring on the whole earth scale on the basis of data obtained from a sensor mounted on a satellite undergoing excursion around the earth. A satellite located on a position above the equator of the earth spinning about the earth axis, is set to an equator orbit directed in a direction opposite to the direction of the earth spin. Thus, a region a is produced on the earth, which permits scanning of a point a plurality of times. The whole region data of the earth is thus detected over a south/north direction angle by progressively integration processing intermittently obtained reflected light components from regions b, c, d, . . . of the earth surface one region to another.