Orbit determination simulation for korea pathfinder lunar orbiter using sequential estimation approach

The Korea Pathfinder Lunar Orbiter (KPLO) is Korea’s first lunar exploration program developed by the Korea Aerospace Research Institute and will be launched in late 2020. The KPLO will employ a 3.5 phasing loop and 100 km altitude lunar polar orbit for lunar transfer and mission phases, respectively. In this study, we introduced orbit determination (OD) strategy of KPLO flight dynamics system and demonstrated OD simulation results using sequential estimation technique. The lunar transfer trajectory and mission orbit of KPLO were simulated by STK and KPLO tracking measurements were generated by ODTK using simulated trajectory and ground station configuration including two Deep Space Networks and Korea Deep Space Antenna. For the trans-lunar phase, the orbit prediction (OP) results at the time of perigee maneuvers were presented for stable maneuver execution. For the lunar mission phase, OD and OP results were investigated for payload data processing and mission operation and planning. For OD accuracy assessments, the position uncertainty and orbit overlap precision were utilized. The uncertainties of Keplerian elements and the differences between estimated and true orbits were analyzed for evaluation of OP performance in trans-lunar and mission phases, respectively. Finally, we confirmed that the simulated OD and OP performance addresses the orbit requirements of KPLO. This study provides a useful guideline for the operation of KPLO for trans-lunar and lunar mission phases.