[P-CG18] Future missions and instrumentation for space and planetary science

[PCG18-06] Operation and onboard data processing of the magnetometers (MGF) on BepiColombo MIO

*Ayako Matsuoka¹, Wolfgang Baumjohann², Werner Magnes², Hans-Ulrich Auster³, Manabu Shinohara⁴, Yoshimasa Tanaka⁵, Akiko Fujimoto⁶, Daniel Schmid², David Fischer², Yasuhito Narita², Masaki Matsushima⁷, Go Murakami⁸ (1.Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of Science, Kyoto University, 2.The Space Research Institute, OeAW, 3.Technical University of Braunschweig, 4.National Institute of Technology Kagoshima College, 5.National Institute of Polar Research, 6.Kyushu Institute of Technology, Faculty of Computer Science and Systems Engineering, 7.Tokyo Institute of Technology, 8.ISAS, Japan Aerospace Epoloration Agency)

Keywords:magnetometer, Mercury, BepiColombo

By BepiColombo mission we aim to understand the essential properties of the Herman intrinsic magnetic field and physical process occurring in the Herman magnetosphere. To achieve our aims, we installed a dual magnetometer on Mercury Magnetospheric Orbiter (MMO, MIO), outboard (MGF-O) and inboard (MGF-I) magnetometers, which are developed by European and Japanese groups, respectively. One of the purposes of dual magnetometer is the redundancy, in addition to the separation of the artificial magnetic signal from the natural signal. The two magnetometers are operated independently for the complete redundancy, while the onboard software for the data processing and the output data format are exactly same. Since the telemetry budget for the MIO MGF is strictly limited, the onboard software pre-processes the data (e.g., fitting to the spin-period sinusoidal variation and definition of the least-significant-bit according to the field intensity) and effectively compresses the data before transmitting to the Earth.
BepiColombo was launched in October 2018 and is now cruising in the interplanetary space. It will be inserted into the orbit around Mercury in 2025 after flybys with the Earth, Venus, and Mercury. The MGF-O and MGF-I sensors are placed at the tip and in the middle, respectively, of the 5m long MAST of the MIO spacecraft. During the cruising, the MAST is stored in a container, and the two sensors are located nearby the surface of the spacecraft. Although the magnetic noise radiated from the MIO spacecraft is well restrained, the sensors are considerably interfered by the components on MIO. Moreover, since MIO, MPO (Mercury Planetary Orbiter) and a transfer module (MTM) are stacked during the cruising, MGF sensors suffer strong magnetic noise from MPO and MTM as well. Nevertheless both MGF-O and MGF-I are operated and measure the magnetic fields at flyby events. Some of the interference noise emerge as the difference between MGF-O and MGF-I data, and can be distinguished also by the comparison with the magnetic field data from MPO. The MGF team is making much efforts to evaluate and remove the interference noise so that we could identify natural phenomena in the space around planets. (The details about the data 'cleaning' will be presented in separated talks)
In this talk we present the onboard data processing for MIO MGF, report the operation of the magnetometers at flyby events, and discuss the perspectives about the observation in the orbits around Mercury.