Research On Modelling Technology Of Space Debris Environment Engineering Model In Low Earth Orbit

With the evolution of human aerospace technology, space debris on the Earth orbit keep increasing gradually and have became a serious hazard to on-orbit spacecrafts. Spacecrafts could stay away the impact risk of large cataloged objects using collision detection and orbital avoidance. With regard to small unable cataloged debris, construct space debris environment engineering model to describe their temporal and dimensional distribution. Based on risk assessment, spacecrafts could devise reasonable defend structure and resist hypervelocity collisions. There are various mature foreign engineering models, but the modelling data and data processing approach are not totally open. The latest ORDEM series model is not public to us. The development of spaceflight activities raise urgent requirements to establish our own engineering model.Based on the current situation mentioned above, this paper build engineering model from all kinds of debris source in low Earth orbit region, including modelling data acquisition, modelling data mathematical processing method, and engineering model modelling approach and evaluation of model precision, etc. The main research contents include:First, analysis source models and acquire the distribution of debris size, area-to-mass ratio and velocity increment for different sources, confirms the characteristics of different debris sources.Second, propose space debris long-term orbit propagation without considering periodic perturbation, provides an effective orbital evolution tool for getting modelling data from debris source model. We analysis the long-term effects of the zonal harmonics J2, atmospheric drag, solar radiation pressure and luni-solar attraction basing on first-order orbital perturbation theory. Derivation the long-term orbit evolution for different altitude range based on interaction height of atmospheric drag. The comparison between the results of this paper and STK software shows that the long-term orbit propagation has reliable accuracy and efficiency.Third, based on three-dimensional discretization of the Earth’s outer space, propose a new orbital elements discretization algorithm to calculate residence probability of debris in the bin, then obtain effective spatial density and flux computing method. The residence probability for debris pass through different bins is the basic difficult point. The method by computing residence time of debris in the bin to get residence probability will cost a great quantity of time and the efficiency is extremely low. To improve efficiency, we get a series dispersed points along the debris trajectory, residence probability of debris in the bin is calculated by "static" function with a single parameter of orbital dispersed quantity, then get new algorithm to compute spatial density and flux. The algorithm avoids the calculation process of residence time, improve the computational efficiency greatly.Four, based on historical cataloged object data and ejecta and paint flakes model, establish ejecta and paint flakes statistics events data espectively, predict future events data based on an eight-year-cycle model, combine with events data and orbital long-term evolution algorithm, simulation and generation space debris environment evolution data for all kinds of debris sources, provide modelling data source for building engineering model. Based on historical cataloged object data and the respective characteristics of ejecta and paint flakes, establish 1957~2010 ejecta and paint flakes statistics events data. For the trend of future space debris environment, introduce the thought of source events data 8 years cycle, establish 2011~2050 events data for all kinds of debris sources. Combin with space debris long-term orbital evolution algorithm, the latest ESA source models and various source events data, simulation and generation all kinds of space debris environment evolution data.Five, establish independent low Earth orbit space debris environment engineering model LEO-SDEEM and verify the accuracy of the model, analyzes the influence of atmospheric rotation on the engineering model prediction accuracy. Modelling data is the simulated space debris environment evolution data for all kinds of source, data processing method is orbital elements discretization algorithm, using the research results mentioned above, we establish LEO-SDEEM. The calculation precision of LEO-SDEEM is verified through the comparison between our model with typical in-situ detection data and ESA and NASA space debris environment model. With the assumption of atmosphere rotation speed is equal with the Earth’s rotation speed, we analysis atmospheric rotation factor influence on engineering model prediction accuracy. The results show that considering the rotating of atmosphere does not significantly change the amount of space debris. Orbital alltitude and inclination distribution trend for all kinds of debris sources in rotating atmosphere and stationary atmosphere are basically the same. Atmosphere rotating mainly make all kinds of debris source distribution below 1000 km orbital altitude area appeared different degree volatility.Last, replace ESA breakup model with CSBM breakup model, then analysis the output influence of engineering model. The collision fragment evolution data is generated by CSBM model, set up a new engineering model LEO-SDEEM(CSBM) based on the new fragment evolution data. The comparison between LEO-SDEEM and LEO-SDEEM(CSBM) shows that CSBM model has a significant effect for debris lager than millimeter level.For lack of space debris environment actual measurement data especially small debris data, this paper put forward a basic process and method to establish low Earth orbit space debris environment engineering model. Propose an effective long-term orbit propagation. Develop orbital elements discretization algorithm to calculate spatial density and flux. Generate the space debris environment evolution data of fragment, slag, dust, Na K droplets, ejecta and paint flakes. Establish independent low Earth orbit space debris environment engineering model LEO-SDEEM. Analyzes and gives the influence of atmospheric rotation and different parameters distribution of breakup model on the engineering model prediction accuracy respectively. The research provides data support for the protection structure design of spacecraft, and also provides a technology support for further study on high orbit space debris environment, This paper has an effective theoretical guidance and engineering application values.