| Space debris poses a great threat to space security.In recent years,the rapid development of large-scale small satellite constellations has made the need to mitigate space debris more urgent.The Inter-Agency Space Debris Coordination Committee proposed that LEO satellites should be de-orbited to ensure re-entry within 25 years after the scheduled mission has been completed,which is the key to achieving space debris mitigation.Based on the research of satellite maneuver detection method,the thesis studies the identification method of post-of-mission disposal behaviors of LEO satellites,and further studies the behavior evaluation method for satellites to comply with 25-year guidelines.The main work and innovations of the thesis are as follows:Using historical orbital data fitting to obtain the probability distribution of orbital prediction error,a maneuver detection method based on probability distribution of the prediction error is proposed.By analyzing the prediction error of the selected orbital parameter,the anomaly cataloging value is identified from the historical orbital data,which corresponds to the historical orbital maneuver.Since the anomaly detection threshold of the prediction error is constructed by using the probability distribution of the prediction error learned from the historical orbit data,the accuracy of the maneuver detection is significantly improved.In view of the fact that the traditional method mostly uses the anomaly value of the orbit parameter as the detection object and is susceptible to data noise interference,a maneuver detection method based on self-organizing map clustering analysis is proposed.The orbital maneuver of the satellite is detected by identifying anomalous data segments in the historical sequence of orbital parameters.After the historical sequence is segmented and preprocessed,the self-organizing map neural network is used to cluster and analyze each data segment to realize anomaly detection.Taking the anomaly data segment of the orbit parameter as the detection object significantly improves the noise resistance of the method against historical data.Meanwhile,cluster analysis allows the method to obtain detailed information such as the maneuver type while detecting the orbital maneuver.Based on the aforementioned maneuver detection method,a method for identifying post-of-mission disposal behavior of LEO satellites using historical orbital is carried out.According to the requirements of the 25-year guidelines,LEO satellites that cannot be naturally re-entered within 25 years after the end of life require post-of-mission disposal.In the proposed method,the orbital-maneuver-based disposal behavior is comfirmed by identifying de-orbit maneuvers that shorten the orbital lifetime performed prior to satellites decommissioning.The judgment of whether the satellite is decommissioned is achieved through statistical analysis of satellite historical maneuvers.For the disposal behavior based on the drag enhancing device,confirmation is made by identifying a sudden change in the ballistic coefficient caused by deploying the drag enhancing device.Based on the mathematical model of orbital decay caused by drag,the historical values of the ballistic coefficient is reversed from the historical orbit data,and then be used to identify the disposal behaviors.Based on the identification method of end-of-mission disposal behavior of LEO satellites,combined with the theory of orbital life estimation,the method of using historical orbital data to evaluate satellite compliance with the 25-year guidelines is studied.For the satellites that can naturally meet the 25-year guidelines,the orbital lifetime estimation algorithm based on semi-analytic theory is used to determine the orbital altitude boundary of such satellites.For other satellites,based on the detailed analysis of the post-of-mission disposal strategies,the process of analyzing and evaluating the satellite behavior based on the methods in the previous chapters of the thesis is proposed. |
PDF Full Text Request