Abstract
China’s lunar exploration missions have developed and progressed for
more than 13 years. In these missions, Precise Orbit determination (POD)
guarantees successful execution of Chang’e missions, and the basis for
further scientific investigations using radio science data; for example,
recovering the lunar gravity field to explore the inner structure and
detect craters to study the evolutionary history of the moon. This paper
briefly reviews the Chang’e series mission orbit and tracking
measurements. We reprocessed the tracking data and comprehensively
summarized the evolution in POD accuracy and the tracking system
precision from the Chang’e 1 to Chang’e 4 missions. Our results show
that the accuracy of Chang’e 5T1 Doppler measurements reach about 0.35
mm/s and the two-way range measurements 0.2 m, with respect to 1.1 mm/s
and 1.6 m for Chang’e 1. The Chang’e 4 relay satellite achieved POD
accuracy at the meter level, in contrast to the half-kilometer level
accuracy achieved during the Chang’e 1 mission. We can clearly see that
the POD performance and precision of the Chang’e spacecraft are
continuously improving. This research is a reference for future Chinese
Lunar missions, as well as Chinese Mars and asteroid explorations.