基于下一代四星转轮式编队系统精确和快速反演FSCF地球重力场

第一,由于重力卫星编队轨道的稳定性设计是建立下一代高精度和高空间分辨率地球重力场模型的关键,因此为保证下一代四星转轮式编队系统的稳定性,轨道根数的最优设计如下:(1)轨道半长轴a、轨道偏心率e、轨道倾角i和升交点赤经Ω保持不变;(2)每对卫星的近地点幅角ω和平近点角M分别相差180°;(3)初始近地点辐角ω设置于赤道处,初始平近点角M设计于极点处;(4)卫星编队系统椭圆轨道的半长轴和半短轴之比为2:1. 第二,基于下一代四星转轮式编队系统,利用星间速度插值法,通过相关系数(激光干涉测量系统的星间速度0.85、GPS接收机的轨道位置和轨道速度0.95、星载加速度计的非保守力0.90)、观测时间30天和采样间隔10 s,反演了120阶FSCF-1/2/3/4(Four-Satellite Cartwheel Formation)地球重力场,在120阶处累计大地水准面精度为1.162×10^-4 m,较目前GRACE地球重力场精度至少提高一个数量级. 第三,下一代四星转轮式编队系统具有低轨道高度、高精度测量、全张量观测、弱混频效应和强时变信号的优点.

Precise and rapid recovery of the Earth's gravitational field by the next-generation four-satellite cartwheel formation system

Firstly, the orbital stability design of the next-generation gravity satellite formation is very important for precisely developing the Earth gravity field model with high spatial resolution. Therefore, for the sake of guaranteeing the stability of the next-generation Four-Satellite Cartwheel Formation (FSCF), the optimal design of the orbital elements is proposed as follows: (1) the semimajor axis a, orbital eccentricity e, orbital inclination i and longitude of ascending node Ω keep invariant; (2) the argument of perigee ω and mean anomaly M need to have a discrepancy of 180°, respectively; (3) the initial argument of perigee ω should be set at the equator, and the initial mean anomaly must be designed at the poles; (4) the ratio between semimajor and semiminor axes from the elliptical orbit of the satellite formation system is 2:1. Secondly, the Earth's gravitational field from the next-generation FSCF complete up to degree and order 120 is accurately and rapid recovered based on the intersatellite range-rate interpolation method using the correlation coefficients (0.85 in intersatellite range-rate of the interferometric laser ranging system, 0.95 in orbital position and velocity of the GPS receiver, and 0.90 in non-conservative force of the accelerometer), an observation time of 30 days and a sampling interval of 10 s, and cumulative geoid height error is 1.162×10^-4 m at degree 120, which is at least one order of magnitude higher than the accuracy of the Earth's gravitational field from GRACE. Finally, the advantages of the next-generation FSCF are the lower orbital altitude, the higher observation accuracy, the full-tensor observations, the weak aliasing effects, and the strong time-varying signals.