The scientific objective of the MMS mission is to:
Understand the microphysics of magnetic reconnection by determining the kinetic processes occurring in the electron diffusion region that are responsible for collisionless magnetic reconnection, especially how reconnection is initiated.
Specifically, and in priority order, MMS will address three main objectives:
Everyone knows magnets exert forces, but did you know that magnetic fields act a lot like muscles that store and release energy as they tie space plasmas together? Magnetic connections switch in a process called "reconnection" that controls space weather forces and energy flows. The switch occurs in tiny volumes of space called "diffusion regions" where the magnetic field lines take an "X" shape separating magnetic muscles that connect two plasmas from those that do not. MMS will observe how, when and where the magneto-muscular switch occurs and why it is often explosive, especially when one plasma tears free from another.
Mission Links: MMS @ GSFC | SMART @ SwRi