The first Korea lunar orbiter, Korea Pathfinder Lunar Orbiter (KPLO), has been in development since 2016. After launch, the KPLO will execute several maneuvers to enter into the lunar mission orbit, and will then perform lunar science missions for one year. Among these maneuvers, the lunar orbit insertion (LOI) is the most critical maneuver because the KPLO will experience an extreme velocity change in the presence of the Moon’s gravitational pull. However, the lunar orbiter may have a delayed LOI burn during operation due to hardware limitations and telemetry delays. This delayed burn could occur in different captured lunar orbits; in the worst case, the KPLO could fly away from the Moon. Therefore, in this study, the burn delay for the first LOI maneuver is analyzed to successfully enter the desired lunar orbit. Numerical simulations are performed to evaluate the difference between the desired and delayed lunar orbits due to a burn delay in the LOI maneuver. Based on this analysis, critical factors in the LOI maneuver, the periselene altitude and orbit period, are significantly changed and an additional delta-V in the second LOI maneuver is required as the delay burn interval increases to 10 min from the planned maneuver epoch.

1. INTRODUCTION
 2. BURN DELAY OF THE FIRST LUNAR ORBITINSERTION
 3. NUMERICAL SIMULATION RESULTS ANDANALYSIS
 4. CONCLUSION
 ACKNOWLEDGMENTS
 REFERENCES

• Jonghee Bae(Korea Aerospace Research Institute, Daejeon 34133, Korea) Corresponding Author
• Young-Joo Song(Korea Aerospace Research Institute, Daejeon 34133, Korea)
• Young-Rok Kim(Korea Aerospace Research Institute, Daejeon 34133, Korea)
• Bangyeop Kim(Korea Aerospace Research Institute, Daejeon 34133, Korea)