Abstract: By analyzing the orbit data of a long-term running satellite, the evolution laws of infrared earth sensor radiant intensity (IESRI) are concluded for evaluating the performance of infrared earth sensor. The short-term changing of the IESRI depends on the latitude of satellite orbit. The medium-term changing depends on the period of the season of earth. The long-term changing depends on the capability of infrared earth sensor which is attenuated with the running time. The results could be the rules for analyzing the orbit data of IESRI.

Key words: infrared earth sensor, radiant intensity, orbit data, evolution law