Abstract: The model of swingscanning infrared earth sensor (SSIRES) at different orbit altitudes is researched in this paper. By reviewing the swingscanning Process of infrared earth sensor(IRES),two models, as disk model and 3D model are introduced by taking orbit altitude as a variable. The transformation from the earth chord length to attitude angles is established approximately in the condition of spacecraft closing to zero position, so that the models are extended to all kinds of orbits through calibration for interested orbit altitudes .

Key words: infrared earth sensor, orbit altitude, swingscanning, model research