macau science satellite-1, vector fluxgate magnetometer, artificial disturbances, noise features, Science, Geophysics. Cosmic physics, QC801-809, Environmental sciences, GE1-350

The Macau Science Satellite-1 (known as MSS-1) is the first scientific exploration satellite that was designed to measure the Earth’s low latitude magnetic field at high resolution and with high precision by collecting data in a near-equatorial orbit. Magnetic field data from MSS-1’s onboard Vector Fluxgate Magnetometer (VFM), collected at a sample rate of 50 Hz, allows us to detect and investigate sources of magnetic data contamination, from DC to relevant Nyquist frequency. Here we report two types of artificial disturbances in the VFM data. One is V-shaped events concentrated at night, with frequencies sweeping from the Nyquist frequency down to zero and back up. The other is 5-Hz events (ones that exhibit a distinct 5 Hz spectrum peak); these events are always accompanied by intervals of spiky signals, and are clearly related to the attitude control of the satellite. Our analyses show that VFM noise levels in daytime are systematically lower than in nighttime. The daily average noise levels exhibit a period of about 52 days. The V-shaped events are strongly correlated with higher VFM noise levels .