The basic data processing for KPLO gamma-ray spectrometer (KGRS)

Abstract

On August 5, 2022, South Korea's first lunar probe, the Korea Pathfinder Lunar Orbiter (KPLO, DANURI) was launched and entered lunar orbit in December of the same year. The KPLO is currently conducting a mission with the KPLO Gamma-Ray Spectrometer (KGRS) developed by the Korea Institute of Geoscience and Mineral Resources (KIGAM). The primary objective of the KGRS is to collect gamma-ray spectral information on the lunar surface and create an elemental map. This paper discusses the basic processing steps of the KGRS data currently operating in lunar orbit and the data processing results for approximately one year. KGRS data is currently maintained in two categories: TM2 data, and TM3 data. We are also preparing the calibration (CAL) data. In the TM2 data stage, time conversion and correction are performed. In the TM3 data stage, the SPICE (Spacecraft Planet Instrument C-matrix Events) system is used to obtain satellite positional information. All KGRS data being transmitted to the KIGAM is monitored daily. The monitoring program displays and monitors the engineering data such as device temperature and science data such as gamma-ray counts. Monitoring gamma-ray counts allows us to detect events such as solar flares or gamma-ray bursts that could affect the data. Since that kind of data can not represent information on the lunar surface, the data at that time should be excluded from mapping data. To verify the result of the data selection, we compare the gamma-ray count maps before and after the exclusion of these data.