Spacecraft Target Infrared And Visible Radiation Characterics And Its Restrain Methods

Research on radiation characteristics of spacecraft target has very important application values in fields of aerospace technology, space countermeasure, remote sensing detection, and communication-navigation. For space countermeasure the mastery of radiation characteristics restrain technology of spacecraft target is particularly important, which leads to the maitain of a favorable space sueriority. Based on the study on radiation characteristics of spacecraft target, contamination and radiation effects on the radiation characteristics of spacecraft target and the radiation characteristics restrain technology of spacecraft target are investigated in this paper. Details are as follows:1. Infrared radiation characteristics and its environmental effects of spacecraft targetBased on the study on space environment, radiation characteristics of spacecraft target is investigated. According to the internal and external heat flux of spacecraft target, a temperature field model of target is built. The model can be used to calculate the surface temperature distribution of target. If considering the surface characteristics of the target, infrared radiation flux model can be built, which be used to calculate the target infrared radiation flux distribution. Analysis of surface contamination and space radiation effects on spacecraft target is given. Space optical systems surface contamination testing and space radiation testing are designed to study the effects. Surface contamination on spacecraft target mainly makes the surface gray rise. So the infrared radiation characteristics of spacecraft target increase and infrared radiation characteristics of different surface becomes uniform.2. Visible radiation characteristics and its environmental effects of spacecraft targetA visible radiation characteristics model is built. Take a geosynchronous orbit communications satellite of our country for example, the non-sequential ray-tracing method based on Monte-Carlo technique is used to calculate the visible radiation characteristics of the target. The satellite visible radiation characteristics are expressed as irradiance accepted by the observation point detector. Bacause the symmetry of satellite body, the satellite irradiance value accepted by the detector in different observation angles has symmetry property. And the irradiance value is proportional to the square of the distance between observer and satellite. The space radiation effect is an impact of long-term cumulation. Testing and simulation analysis show that the visible radiation characteristics of spacecraft target almost keeps the same in the short-term space radiation. When the period of space radiation is longer than 5 years, the visible radiation characteristics of spacecraft target significantly increases with the time increasing. After the period of 15years space radiation, the visible radiation energy of spacecraft target becomes double.3. Infrared radiation characteristics restrain method of spacecraft targetCryogenic vacuum multilayer thermal insulation film structure is used to restrain the infrared radiation characteristics of spacecraft target in this paper, which is different from existing methods. This method does change the target shape and reduces the target temperature near to the environment temperature.According to the model analysis we find that target's infrared flux was significantly reduced and its peak wavelength shift out of so all kinds of infrared detector window. So the detected probability is decreased.4. Visible radiation characteristics restrain method of spacecraft targetPolyhedral shape and mirror surface design is presented in the paper, which is used to restrain the visible spectral radiation characteristics of spacecraft target. This design decreases visible detected probability of spacecraft target. Examples are given to illustrate the comprehensive application of the method, which shows the excellent restrain effect.5. Heat transfer analysis and testing study of multilayer film structure used in infrared radiation characteristics restrain of spacecraft targetBased on the the heat transfer mechanism, heat transfer analysis of cryogenic vacuum multilayer thermal insulation film structure used in restrain infrared radiation characteristics restrain of spacecraft target is given in this paper. The classical radiation heat transfer models is built. The models are extremely instructive in the design and application of the film structure. For the perpose of verifying the infrared radiation characteristics restrain performance of the film structure, ten-layer Al/Kapton/Ge film structure was chosen to be tested in the space environment simulation testing. The results show that spectral radiation intensity becomes two orders of magnitude lower and its peak wavelength shift to longer than 20μm. Because of the inevitable contact heat transfer and radiation heat transfer from other heat sources, the testing results are not so good as analysis results of models. Contact heat transfer should be minimaized in application.