Data processing and quality evaluation for the vector magnetic field measurement on the Macau Scientific Satellite-1 mission

Macau Scientific Satellite-1 (MSS-1) is a low-Earth orbit (LEO), low-inclination satellite mission launched on May 21, 2023. Its primary scientific objectives are to separate geomagnetic sources and characterize magnetic fields near the Earth's surface. To achieve these goals, high-quality vector magnetic data were obtained through rigorous preflight and in-flight calibration procedures. This study outlines the key workflow for magnetic data processing, as well as the format, naming conventions, and content of the data products, which serve as valuable references for scientific research. For orientation calibration, an attitude combination method was developed and implemented, achieving a weighted standard deviation of approximately 1.5 arc sec for the inter-boresight angle between combined quaternions and quaternions from three cameras of star tracker. Additionally, a joint estimation approach was employed that combined Euler angles and geomagnetic field model coefficients. To evaluate the quality of the data, comparisons were conducted between MSS-1 and the Swarm satellite to capture typical space magnetic disturbances. Closest to the orbital intersections, the results indicate a maximum difference of approximately 3 nT in the vector components, observed under various conditions. Consistency in describing geomagnetic storms was also demonstrated between MSS-1 data and specialized geomagnetic indices, with correlation coefficients greater than 0.91 for all cases. It can be concluded that the vector magnetic data products generated by the MSS-1 processing workflow are of high quality. This workflow is adaptable for use in the upcoming MSS-2 mission or other nonpolar LEO satellite missions.