| In modern times, various aircraft in the space environment plays an increasingly important role in both military and civilian, and the identification and detection of these spatial objects are also very significant. The infrared characteristic of space targets is a major criterion to detect and identify these targets. In this paper, the infrared radiation characteristics and the infrared scattering characteristics to background radiation sources of warhead and decoy targets are studied. The main contents of this paper are:1?As the important infrared radiation background source of space targets, the model of global surface temperature and emissivity, cloud top temperature is proposed based on land, ocean and atmospheric products data of MODIS. After the data of temperature and emissivity is obtained, the infrared radiation model at 3~5?m and 8~12?m infrared bands is established. Because the cloud top height affects the properties of clouds, the model of the cloud top height is established and the distribution characteristics of it are analyzed.2?When the radiation of the earth surface and cloud top transfers to the space target, it will be decayed by atmosphere, and atmosphere will emits radiation outwards. These are calculated and analyzed by MODTRAN calculation software.Through polynomial fitting of transmittance and path radiation which calculated by MODTRAN, polynomial fitting function in different bands on the observation angle is obtained. An engineering algorithm of transmittance is used to obtain the transmittance between targets and cloud top.3?The temperature field of the target surface is obtained by using the thermal balance equation of target nodes, and the infrared radiation field at 3~5?m and 8~12?m infrared bands is established. The temperature of target is compared by using radiation angle coefficient and earth surface bin method. The changes of temperature field and infrared radiation field are analyzed in the case of the target with the spin, the different height, different target shape, and so on.4?The radiation of the sun, the earth and the sun radiation reflected by the earth is the main infrared background radiation of space targets. In order to calculate the scattering intensity of space targets to these background radiation, the method to obtain bidirectional reflectance distribution function of different materials by using Kirchhoff approximation method is introduced. The integrated scattering intensity of target to different infrared backgrounds is calculated by using different methods. The change of the integral scattering intensity is discussed when the surface of target is Lambert surface or non-Lambert surface. In order to make the result more reality, the real earth infrared background is brought into calculation.5?After the analysis of a single target, the situation of group targets is analyzed, because the warhead and decoy always fly together. Overall temperature and infrared characteristics of the group targets composed by two targets or three targets are studied and are compared with the case of a single target.In this paper, the infrared background radiation model of space targets is established and the infrared characteristics of single or multiple spatial warhead and decoy targets are analyzed. It provides theoretical support for target detection and recognition of true and false targets. |
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