Magnetic Reconnection as Revealed by the Magnetospheric Multiscale Mission
Résumé
The NASA Magnetospheric Multiscale (MMS) mission has completed its prime mission observations and has now entered an extended mission phase. During the two-year prime mission MMS made fundamental advances in our understanding of magnetic reconnection as enabled by its unprecedentedly high-resolution plasma and field measurements, which were made from 4 identical spacecraft in tetrahedral formations ranging down to 7 km. The primary objective of MMS is to understand reconnection at the electron scale, and this objective was accomplished by detailed analysis of 32 electron diffusion regions at the dayside magnetopause and a significant number in the magnetotail, which are still being captured and analyzed. Significant interplay between theory and experiment has occurred throughout the mission leading to the discovery of agyrotropic "crescent-shaped" electron velocity-space distributions, which carry the out-of-plane current; the electron pressure tensor divergence, which produces the reconnection electric field; standing oblique whistler waves, which produce intense dissipation in sub-gyroscale regions near the X-line and electron stagnation point; beam-plasma interactions leading to whistler-mode and Langmuir waves; electromagnetic drift waves leading to corrugated magnetopause current sheets, and numerous other new reconnection-related phenomena. In this talk the many new aspects of reconnection discovered by MMS will be placed into context and used to evaluate our current level of understanding of this universally important space plasma phenomenon.