Orbit determination and accuracy evaluation of Tianwen-1 probe
For China's first Mars exploration mission,Tianwen-1,high accuracy orbit determination is the cornerstone for ful-filling engineering goals and scientific exploratory objectives.This study adopts a variety of orbit determination approaches based on the characteristics of the orbit,the dynamic environment,and the observational quality of different stages.It then evaluates the orbit accuracy by comparing overlapping arcs.Modeling errors for solar radiation pressure and attitude control thrust are the main obstacles preventing the high accuracy orbit of Tianwen-1.Some model errors can be removed by resolving the solar radiation pressure coefficient and empirical acceleration parameters during the orbit determination estimation.Howev-er,because of the special spacecraft attitude,the combined estimation of the solar radiation pressure coefficient and empirical acceleration parameters leads a clear coupling relationship,but adding a priori constraint information is a way to decrease the correlation between them.In the interplanetary cruise stage,the orbit accuracy is better than 4 km,1 km in the parking stage,and 100 m in the relay communication stage,according to the results of an overlapping orbit.Furthermore,the accuracy of two-way range measurement is about 0.5 m,the two-way Doppler measurement is about 0.2 mm/s at 1 s integration time,and the VLBI delay measurement is around 0.3 ns.
Tianwen-1precise orbit determinationsolar pressureattitude control thrust
NETL
NSTL
万方数据
