The flight model for the MSA (Mass Spectrum Analyzer) has been completed.

The Mass Spectrum Analyzer (MSA) is one of the 13 instruments onboard the MMX spacecraft, and will make measurements of the masses of ions (charged particles) and the magnetic fields in the vicinity of Phobos and Mars. Ions that originate from the surface of the Martian moons and the atmosphere of Mars exist around Mars due to interactions with the solar wind. MSA will remotely examine the surface material of the moons and will directly observe the escape of the Martian atmosphere, while monitoring the solar wind. These observations aim to put constrains on models of the evolution of the Martian atmosphere, and the origin of the moons.

Left: The MSA FM (flight model): the ion mass spectrometer, (MSA-S: back), two magnetometers (MG-S1, S2: front), and the electric box (MSA-E: right). Right: Group photo at the time of the MSA handover. From the left, Sawada Hirotaka, Nagamine Kenta (JAXA), Tanaka Isao, Imaizumi Yusaku, Kataoka Kazuhiko (Meisei Electric Co., Ltd.), Arai Miyuki, Sato Yuhei (MELCO).

The preliminary design for the MSA was started by Meisei Electric Co., Ltd. in December 2019. After the development of the engineering model (EM), and Critical Design Review (CDR), we had the Post Qualification Review (PQR) and Pre-Shipping Review (PSR) which confirmed the completion of the development for the Flight Model (FM) in August 2024. The FM for the MSA was then transported to Mitsubishi Electric Corporation Kamakura Works and officially handed over after the post-transport checks.

The MSA will be integrated into the spacecraft exploration module, and will join the system preflight test.

MSA Principal Investigator (PI) Yokota Shoichiro
Graduate School of Science, Osaka University

MSA is an ion mass spectrometer and magnetometers developed from previous instruments for the Kaguya and BepiColombo missions. The ion mass spectrometer has an extremely high resolution, that is sufficient to distinguish between a wide variety of ion species originating from the Phobos surface and the Martian atmosphere. The magnetometer uses a fundamental mode orthogonal fluxgate technique that achieves a significantly downsized and lightened sensor, and will contribute to improving the accuracy of ion observations. We would like to express our sincere thanks to all members, including those from the companies in charge of the MSA development.

Manufacturer of MSA Tanaka Isao
Space Defense Division, Meisei Electric Co., Ltd.

In cooperation with Dr Yokota from Osaka University for the ion mass analyzer, Professor Matsuoka from Kyoto University for the magnetometer, and Dr Murata from JAXA, the EM and FM for the MSA were tested and evaluated, and the development has been completed. We hope that the MSA will operate without any issues in the upcoming comprehensive tests and in orbit, and that the observation data will be obtained. We would like to express our sincere gratitude to all members of JAXA, the universities, and everyone who was involved for their support and cooperation.