MMS mission successfully launched

NASA has announced the successful launch of its MMS mission (Magnetospheric Multiscale) on 13 March at 03:44 (Paris Time). This mission is designed to study magnetic reconnection, a fundamental process through which charged particles are heated and accelerated to great speeds by magnetic energy. MMS will fly a formation of four satellites to measure charged particles and electromagnetic fields in the magnetosphere, the ionized environment where particle movement is controlled by Earth’s magnetic field. Many U.S., European and Japanese research laboratories are involved in the mission, notably two French laboratories—the LPP plasma physics laboratory (CNRS/Ecole polytechnique/UPMC/Université Paris-Sud/Observatoire de Paris) and the IRAP astrophysics and planetology research institute (CNRS/Université Toulouse III Paul Sabatier)—supported by CNES.

Magnetic reconnection is considered to be a common process in the Universe that is observed for example in active galactic nuclei, pulsars, stellar accretion disks, solar flares and planet magnetospheres. It is one of the mechanisms through which energy from a magnetic field heats and accelerates charged particles. It plays a key role in exchanges of energy between the Sun and our planet. The phenomenon is also studied in the lab, notably in research on the stability of magnetic plasma confinement in fusion reactors (tokamaks). A lot of theoretical and numerical work is being done, particularly at LPP and IRAP, to better understand it.

The goal of the MMS mission is to study magnetic reconnection, particle acceleration and plasma turbulence at electron scale, in situ in Earth’s magnetosphere. In this environment, collisions between particles are so rare that they cannot release the energy required for magnetic reconnection to occur.

Like the European Cluster mission, the four MMS satellites will fly in a tetrahedral formation to acquire three-dimensional measurements of plasma and electromagnetic fields. By measuring particles at very high temporal resolution—30 milliseconds for electrons and 150 milliseconds for ions—and with a separation distance between the satellites of 10 to 100 kilometres, MMS will enable scientists to see the rapid dynamics of electrons and understand their role in the process of magnetic reconnection and in the sudden release of energy in hot plasmas in space and in the lab.


France, through LPP and IRAP, supplied two instruments and instrument elements for MMS. The first instrument will study rapid variations in Earth’s magnetic field and the second will study ions and electrons. LPP designed the Search Coil Magnetometers (SCMs) that will measure magnetic field fluctuations, and their calibration software. IRAP was involved in producing the eight instruments that will detect charged particles. With support from CNES, the two French laboratories will also be playing an active role in analysis and interpretation of science data.