Analysis of Simulation Results of Orbit Observation of Stellar Occultation Technology
SUN Ming-chen1, 2, WU Xiao-cheng1*, HU Xiong1
1. National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：Stellar occultation is an effective means of measuring the trace components density, temperature, aerosol, etc. on the Earth and other planets using stellar spectra. Thedetection principle mainly shows different absorption characteristics in different positions of the stellar spectrum according to different atmosphericcomponents, and the specific performance is as follows: the ultraviolet band can measure ozone, oxygen, hydrogen, etc., the visible spectrum can detect nitrogen dioxide, nitrogen trioxide, oxygen, etc., and infrared can detect water vapor, aerosol, methane, carbon dioxide, oxygen and so on. The realization process of the stellar occultation is: when the LEO satellite and the stellars are located on both sides of the earth, the light emitted by the stellar passes through the absorption and scattering of the earth’s atmosphere, and is received by the LEO on the other side, which constitutes an occultation observation. According to the spectral flow, the magnitude range of stellars is obtained, and the distribution of stars in the celestial coordinate system and different spectral types are given, as well as the atmospheric components detectable by each spectral type. The stellar-LEO occultation orbit observation simulation is carried out using the relative positions of the stellars and LEO satellite in the ground-solid coordinate system. The basic process is: firstly, reading the orbital position of the LEO satellite and the position of the target stellar, setting the simulation time of 24 hours, and then judging whether it is in the occultation state. When the occultation starts, parameters of occulation, such as the latitude and longitude are calculated and output until the end of the simulation time, which involves the process of the stellar transformation from the celestial coordinate system to the ground-solid system and calculation of LEO satellite orbit, occultation point latitude and longitude, etc. Through calculation and analysis of the daily measurement, global distribution, duration, and drift velocity of the occultation event according to the simulation process, the following results are obtained: (1)The target stellars have a certain number of distributions in the whole sky zone. (2)During the 24-hour orbital simulation of the stellar occultation, the daily observation is 5 563 times, including 2 737 rising occultations and 2 826 descending occultations. (3)From the perspective of global distribution, occultation events are mainly distributed at low latitudes, with the least two poles, the other latitudes are equal, the longitude direction is evenly distributed. (4)According to the azimuthal distribution, the normal occultation ratio is 78.25%, the average duration is 1.5 minutes, and horizontal drift of the tangent point is between 18 and 600 km. (5)The side occultation is 21.75%, longer than the normal occultation, the horizontal drift speed of the tangent point is large, and the azimuth angle is also large. The above results provide theoretical guidance for satellite orbit design and detection of load design.
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