Abstract:
Objectives: The lunar libration parameters are important parameters that affect the positioning
accuracy of the Chang'E ‐3 lander. Studying the lunar balance dynamic parameter estimation methods is of
great significance to the development of lunar exploration projects in China. At present, the lunar libration
parameters is calculated by the ephemeris method, but this method cannot guarantee the positioning accura‐
cy of the lander. Methods: We first establish the expressions of the very long baseline interferometry
(VLBI) time delay and delay rate with the changes of the landers position, velocity, then based on VLBI
technique, the lunar physical libration parameters are calculated by using weighted least square adjustment
method.Results: Compared with the interpolation results of the DE421 ephemeris, the improvements of
the Euler angles Ω, i and μ are compensated to -0.692 4″, 0.009 6″ and -0.009 7″ respectively.Based on
the lunar physical libration parameters ,the position and velocity of the lander were solved, the results show
that the positioning accuracy of the lander can be improved in X,Y,Z directions by 24.204 m, 0.405 m,
1.996 m respectively. The estimation accuracy of the velocity error is also improved by 0.010 6 m/s,
0.013 5 m/sand 0.007 2 m/s in X,Y,Z directions.Conclusions: This paper provides strong reference for
the related research on the calculation of the physical libration parameters in the future.
