Analysis Of Space-based Space Target Infrared Characteristics And Space Target Working Condition Inversion

With the improvement of space situation awareness’s function in national security,the existing ground-based space target visible detection system,ground-based space target infrared detection system and space-based space target visible detection system develop maturely.It is necessary to invest a new method of space situation acquisition to cover the insufficiency of these space situation acquisition methods.An essential method to gain fully space situation awareness,space-based space target infrared characteristics and obtainment method is studied in this dissertation.Because of the complex orbital thermal radiation,space target will endure a temperature alternation of tens and even more than one hundred centigrade.Multi-layer issulation materials are commonly used in space target to ensure the loads with operating in proper temperature.In the meantime,the waste heat of the inner space target would be unable to ejecte.A thermal control system is commonly used to transfer waste heat to the radiator in the outer surface of space target,by with the waste heat get radiated.The areas of space target like radiator can be treated as an infrared characterization of space target.By observing these iufrared characterization,the inner working condition with which these characterization is tied can be deducted.The main contents of this paper are as follows:1.A model of space target infrared radiation characteristics based on radiant dissipation is built.Aiming at infrared characterization of space target,like radiators,the outer surface of space target is devided into normal area and dissipating area,and energy equations are built separately,with which the radiation characteristics are researched.The choice working spectrum of space target radiation measure system is researched,and the result shows that longwave spectrum is better because of higher radiation intensity.2.An image denoise method based on threshold statistics and a nonuniformity correction method based on registering statistics are proposed.Because the background of space based space target images are clean,confidence interval of a certain confidence level of additive noise is accessable by counting the background pixels,and thereby calculate the confidence interval of a certain confidence level of signals.Simulation result shows that this method can improve local SNR by 27.93,and denoise effect is much better than mean filter,median filter and wavelet threshold denoise.By using the randomness of gain drift after infrared imaging system calibration,confidence interval of a certain confidence level of the ratio between second~nth images and first image is accessable by statistics,and the first image can get corrected because the statistic mean is know.Simulation result shows that this method can improve local SNR by 29.13 and reduce non-unformity effectively.3.The influence of working spectrum,imaging system noise and point spread fuction(PSF)noise in space based space area target temperature reversion is researched.Radiant temperature measurement,colorimetric temperature measurement and spectral temperature measurement are commomly used temperature measurement methods.Conclusions are drawed by reversing radiator’s temperature in different working spectrum,different imaging system noise and different PSF noise,which are that radiant temperature error in midwave is smaller than that in longwave,colorimetric temperature error in longwave is smaller than that in midwave,errors of radiant temperature,colorimetric temperature and spectral temperature are increasing in a row with same imaging system noise,and the error of temperature in midwave is smaller than that in longwave.4.The influence of environment radiation fluctuation,coating materials degradation and detector noise to the minimum resolvable dissipating power difference is researched and an algorithm to calculate the change rate of dissipating power is proposed.The minimum resolvable dissipating power difference can be obtained by comparing the temperature difference caused by environment radiation fluctuation,coating materials degradation and detector noise.Simulation result shows that The maximum value minimum resolvable dissipating power difference is[-0.1622W,0.1496W]with solar radiation fluactance of±1%,[-0.1591W,0.1467W]with solar absorption change of?0.01,[-2.2219W,2.2276W]when gain noise is N(1,0.01)and confidence level is 99.37%and[-0.0490W,0.0613W]when offset noise is N(10~5,10~4)and confidence level is 99.37%.Inner dissipating power and temperature in energy equation change when dissipating power of radiator changes.Thereby the change rate of dissipating power can be calculated by calculating four temperatures of radiator of two same periods by differencing each two energy equation and then solve equation set afterward.When dissipating power change rate is 1W/s,the result of this algorithm is 0.9754W/s,and ralative error is 2.46%.