超低轨卫星星座恢复短周期时变重力场的模拟分析

Simulation analysis of short-period time-varying gravity field in recovery of very-low orbit satellite constellation

  • 摘要: 相比下一代重力卫星任务的Bender星座,以通导遥为主要目标的超低轨卫星(Very Low EarthOrbit,VLEO)星座能够在短时间内进行大规模地面覆盖,增加了时变重力场的时空采样,有望降低混频效应,提升重力场时变信号的探测能力。本文研究模拟了Bender星座和250 km高度处由300颗卫星组成的VLEO星座的观测数据,开展了时变重力场信号恢复性能的闭环仿真模拟实验,结果表明:在不考虑观测量噪声时,相比Bender星座,VLEO星座可有效降低混频效应对时变重力场建模的影响;对于7日时变重力场解,在VLEO星座卫星轨道精度为1 cm、Bender星座星间测速精度10 nm/s,并考虑混频误差的情况时,VLEO星座可恢复15阶以内的有效信号(信噪比达到1),并且在8阶以内略优于Bender星座;当VLEO卫星定轨精度在1~10 cm的情况下,在Bender星座的基础上引入VLEO星座联合解算,可有效降低解算结果的混频效应和南北条带误差,提升短周期时变重力场的恢复性能。

     

    Abstract: Objectives: In comparison to the Bender constellation in the next generation of gravity missions, the Very Low Earth Orbit (VLEO) constellation with the main objective of conducting communication, navigation, and remote sensing has the capability to achieve extensive ground coverage in a short time, increase the spatio-temporal sampling of time-varying gravity field, and is expected to reduce the aliasing effect and improve the detection capability of time-varying signals in gravity field. Methods: We simulated observation data obtained from a VLEO constellation, comprising 300 satellites orbiting at an altitude of 250 km, along with the Bender constellation. Through closed-loop simulation experiments using the short-arc integral method, we compared and analyzed the performance of short-period (7-day) time-varying gravity field recovery of different constellations under varying error conditions. We also studied the impact of varying noise levels, orbit configuration, and aliasing effects on the results. Results: When not accounting for observed noise, the VLEO constellation, as compared to the Bender constellation, is able to effectively mitigate the impact of aliasing effects on the modeling of the time-varying gravity field. For the 7-day time-varying gravity field solution, if the orbital accuracy of the VLEO constellation is 1 cm, and the inter-satellite velocity measurement accuracy of the Bender constellation is 10 nm/s, taking into account the aliasing error, the VLEO constellation has the capability to effectively recover signals up to degree 15, and slightly outperforms the Bender constellation up to degree 8. With the orbit determination accuracy of VLEO satellites ranging from 1 to 10 cm, the addition of the VLEO constellation to the Bender constellation can effectively minimize the aliasing effect and the northsouth striping characteristics in the solution results, thereby improving the recovery performance of the shortperiod time-varying gravity field. Conclusions: The comparative test results show that VLEO constellation can reduce aliasing effect by increasing spatiotemporal sampling, and its introduction can make Bender constellation recover better time-varying gravity field results.

     

/

返回文章
返回