This paper presents a kinematic ephemeris generator for Korea Pathfinder Lunar Orbiter (KPLO) and its performance test results. The kinematic ephemeris generator consists of a ground ephemeris compressor and an onboard ephemeris calculator. The ground ephemeris compressor has to compress desired orbit propagation data by using an interpolation method in a ground system. The onboard ephemeris calculator can generate spacecraft ephemeris and the Sun/Moon ephemeris in onboard computer of the KPLO. Among many interpolation methods, polynomial interpolation with uniform node, Chebyshev interpolation, Hermite interpolation are tested for their performances. As a result of the test, it is shown that all the methods have some cases that meet requirements but there are some performance differences. It is also confirmed that, the Chebyshev interpolation shows better performance than other methods for spacecraft ephemeris generation, and the polynomial interpolation with uniform nodes yields good performance for the Sun/Moon ephemeris generation. Based on these results, a Kinematic ephemeris generator is developed for the KPLO mission. Then, the developed ephemeris generator can find an approximating function using interpolation method considering the size and accuracy of the data to be transmitted.

1. INTRODUCTION
2. A KINEMATIC EPHEMERIS GENERATOR FOR THEKPLO
    2.1 Ground Ephemeris Compressor
    2.2 Onboard Ephemeris Calculator
3. PERFORMANCE ANALYSIS
    3.1 Performance Tests of Spacecraft Ephemeris Generation
    3.2 Performance Tests of the Sun/Moon Ephemeris Generation
4. CONCLUSIONS
REFERENCES

• Min-Sup Song(Astrodynamics and Control Lab., Department of Astronomy, Yonsei University, Seoul 03722, Korea)
• Sang-Young Park(Astrodynamics and Control Lab., Department of Astronomy, Yonsei University, Seoul 03722, Korea) Corresponding Author
• Youngkwang Kim(Astrodynamics and Control Lab., Department of Astronomy, Yonsei University, Seoul 03722, Korea)
• Jo Ryeong Yim(KPLO Mission and System Team, Korea Aerospace Research Institute, Daejeon 34133, Korea)