Calibration and Testing of the Mercury Ion Analyzer (MIA) Sensor of the Mercury Plasma Particle Experiment (MPPE) onboard the BepiColombo Mission to Mercury

Abstract: Mercury is the closest planet to the Sun in the Solar System and because of this, its study has been a challenging task. BepiColombo/MMO is an orbiter part of a mission to Mercury with the goal of studying Mercury's magnetic field and magnetosphere. The orbiter is being developed by ISAS-JAXA. The studies are done using a five instruments payload. One of them is the Mercury Plasma Particle Experiment (MPPE) which will study low and high energy electrons/ions and energetic neutrals. The low-energy ion measurements are done using the Mercury Ion Analyzer (MIA) sensor, which is part of the MPPE.
The MIA sensor requires calibration and testing to ensure its adequate operation. The testing will prove that the MIA sensor will be able to operate adequately in the Bepi-Colombo mission. This thesis work covers a series of factors that are required to verify the performance of the sensor. These factors are the degradation of the Micro-Channel Plate over time, the survival to vibration and thermal vacuum environments and the development of the software model of the sensor. These factors were evaluated with a MCP life test, qualification testing on the form of vibration and thermal vacuum tests and comparison of the sensor model response to the expected plasma environment around Mercury.
The results of the MCP life test show that the MCP degrades faster at high temperatures, however, it will be able to survive the two year mission to Mercury. The qualification testing showed that the MIA sensor is able to withstand the vibration conditions in the mission. However, it will be until a new thermal vacuum test is done that it will be considered that the MIA sensor can withstand the expected thermal conditions. Finally, the response of the software model of the MIA sensor is in accordance to the expected plasma environment around Mercury. Therefore, it could be used to test the accuracy of the velocity moments calculation of the MDP1 software. Overall, the calibration and testing of the MIA sensor still continues. However, the results so far show that it will probe that it can operate under the conditions that the BepiColombo mission requires.