Solar Radiation Pressure Modelling For BeiDou Navigation Satellites

Since 1990 s,Global Navigation Satellite Sstems(GNSSs)have not only provided the basic services of positioning,navigation and times to their users,but also contributed as the important section of the Earth observation technology to the satellite geodesy,establishment and mataining of the reference frame etc.GNSS has never stopped its step forward nowdays.As a strategic and essential resource for China,the BeiDou satellite navigation system(BDS)has experienced technology accumulation for several years,and its basic services have moved from the regional to global coverage recently.The satellite orbital parameters are the core information of the GNSS which provides a space-based reference frame.The high-precision satellite orbit determination depends on the geometric observation conditions and the dynamic model accuracy.For navigation satellites at altitudes of tens of thousands of kilometers,apart from the attractive forces of the Earth and other planets,the influence of solar radiation pressure(SRP)is largest.During the process of the precise orbit determination(POD)for navigation satellites,the observation model along with the orbit dynamic model are both important.Domestic and foreign researchers have conducted extensive investigation and study on the correction of related geometric errors and the refinement of dynamic models including SRP.As the representative of the current GNSS,GPS satellites have an orbit accuracy of arond 2 cm.However,as an emerging global satellite navigation system,orbit accuracy of BDS still needs to be further improved.Based on the systematic study and summary of the development history of navigation modeling of other navigation constellation satellites,this thesis focuses on the SRP modling of BDS-2 and BDS-3 satellites,which takes the geomentry,optical characterics and actual yaw attitude of the satellites into consideration.The main contributions of the thesis are summarized as follows:(1)The development status of the POD theory of navigation satellites along with the nonconservative force model for navigation satellites have been summarized and studied.We also study the development history of the SRP modeling of GNSS satellites.(2)The classical SRP models to the POD of BDS-2 and BDS-3 satellites are analyzed.On the basis of summarizing the SRP modeling theory and practice of GNSS satellites,a method for constructing and refining the BDS satellite and SRP was developed.A highprecision SRP models covering the entire constellation from BDS-2 to BDS-3 have been established.Compared with the traditional empirical SRP model,these models take advantageds of not only physical interaction of SRP but also have simple and effective forms.(3)The systematic bias in the orbits is identified,which significantly degraded the POD performance of BDS GEO satellites.In addition,we conformed that omitting the effects caused by C-band comminucation antenna(CA)is the root of this orbit errors.Then the SRP models is modified in the aspects of the actual oritetion of the solar panels and selfshadowing of the CA.The orbit determined with the re-constructed SRP model indicates that the orbit accuracy of BDS GEO satellites can be significantly improved and the orbitangle and sun-elongation-angle depdent errors along with the obvious bias in radial direction can be removed.The absolute orbit accuracy validated satellite laser ranging(SLR)can reach round 10 cm.(4)The POD performance of BDS-2 satellitesthe by the classical ECOM1 and ECOM2 are compared in terms of SLR validations.Based on the analysis of the orbits determined by empirical and analysis models,the systematic errors exsisted in spefic BDS-2 IGSO/MEO satellites are accounted for the thermal rerediation force.Then a compensatory model has been accordingly construted.This model was conformed to be helpful reduce sysmatic orbit errors.The radial orbit accuracy is proved to be improved by approximately 20%.(5)The yaw attitude characteristics of BDS IGSO-6 has been investigated to find a continuous dynamic yaw model is applied for this satellite.We have established a yaw attitude model with specific theroushold and model parameters based on the metadata published by ESA for satellites manufactured by CAST to have an agreement with estimated yaw angle within 5 degrees.In addition,this yaw attitude model is preoved to be effective to reduce observation residuals near midnight and noon point which in turn stabilizing the POD solution and making further refinement of SRP models possible.(6)In order to reduce the effects casued by SRP model deficiency in BDS-3 POD solutions,three compensatory or enhancement SRP models are established and compared based on the geomentry and optical parameters of the satellite body along wth real tracking data collected from ground stations.As part of the products obtained from(modified)abjustable box-wing model,these three methods which are based on SRP acceleration construction by fourier transformation,calibrated optical paramters and cuboid satellite body compensatory models have been implemented.Using of the a priori model based on the above three models is efftive to remove the the sun-elongation-angle dependent orbit errors.These orbit accuracy in radial direction are finally domestrated to be better than 4 cm.