Modeling Orbit Dynamics of FORMOSAT-3/COSMIC Satellites for Recovery of Temporal Gravity Variations
Modeling Orbit Dynamics of FORMOSAT-3/COSMIC Satellites for Recovery of Temporal Gravity Variations
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DOI：
10.1109/tgrs.2008.2004789
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发表时间：
2008-11
影响因子：
8.2
通讯作者：
C. Hwang;Ting-Jung Lin;T. Tseng;B. Chao
中科院分区：
文献类型：
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作者：
C. Hwang;Ting-Jung Lin;T. Tseng;B. Chao
台美联合使命FORMOSAT-3/COSMIC（COSMIC）卫星的高精度GPS高低跟踪数据可用于重力恢复。目前COSMIC运动学轨道的轨道精度为2厘米，60秒正常点的精度优于1厘米。基于轨道动力学的标准模型，我们对COSMIC航天器上的摄动力进行了建模。力模型数值计算的主要工具是NASA的戈达德GEODYN II软件。考虑到COSMIC航天器没有安装加速度计，通过估计COSMIC航天器在一个轨道周期内的运动学轨道和约化动力学轨道的相关参数，建立了大气阻力、太阳辐射压力和其他微小表面力引起的加速度模型。我们进行了实验的解决方案，随时间变化的位势系数使用一个月的COSMIC运动学轨道（2006年8月）。通过GEODYN II对非重力源力进行适当建模，将剩余轨道摄动（运动轨道和参考轨道之间的差异）假定为随时间变化的地球势系数的线性函数，并将其用作观测值来估计后者。计算了COSMIC重力解和COSMIC与GRACE重力解的组合。COSMIC的解决方案显示了一些众所周知的时间重力签名，但包含文物。结合COSMIC和GRACE解决方案增强了GRACE解决方案中的一些局部时间重力特征。
The precise GPS high-low tracking data from the joint Taiwan-USA mission FORMOSAT-3/COSMIC (COSMIC) can be used for gravity recovery. The current orbital accuracy of COSMIC kinematic orbit is 2 cm and is better than 1 cm for 60-s normal points. We model the perturbing forces acting on the COSMIC spacecraft based on standard models of orbit dynamics. The major tool for the numerical work of force modeling is NASA Goddard's GEODYN II software. Considering that COSMIC spacecraft are not equipped with accelerometers, the accelerations due to atmospheric drag, solar radiation pressure, and other minor surface forces are modeled by estimating relevant parameters over one orbital period from COSMIC's kinematic and reduced dynamic orbits. We carry out experimental solutions of time-varying geopotential coefficients using one month of COSMIC kinematic orbits (August 2006). With the nongravity origin forces properly modeled by GEODYN II, residual orbital perturbations (difference between kinematic and reference orbits) are assumed to be linear functions of time-varying geopotential coefficients and are used as observations to estimate the latter. Both COSMIC and combined COSMIC and GRACE gravity solutions are computed. The COSMIC solution shows some well-known temporal gravity signatures but contains artifacts. The combined COSMIC and GRACE solution enhances some local temporal gravity signatures in the GRACE solution.