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MMS Key Messages

MMS investigates how the Sun’s and Earth’s magnetic fields connect and disconnect, explosively transferring energy from one to the other — a process that occurs throughout the universe, known as magnetic reconnection.

MMS reveals, for the first time, the small-scale 3D structure and dynamics of the key reconnection regions where the most energetic events originate.

By observing magnetic reconnection, MMS studies the ultimate driver of space weather, which affects modern technological systems such as communications networks, GPS navigation, and electrical power grids.

MMS Key Sub-Messages

The four identically instrumented MMS spacecraft fly in an adjustable pyramid-like formation that enables them to observe the 3-D structure of magnetic reconnection. Use of four spacecraft endows MMS with the multipoint measurements needed to determine whether reconnection events occur in an isolated locale, everywhere within a larger region at once, or traveling across space.

Magnetic reconnection taps the energy stored in a magnetic field and converts it rapidly into heat and kinetic energy in the form of individual charged particle acceleration and large-scale flows of ionized gas.

MMS probes both the dayside and nightside of Earth, each with its own unique reconnection characteristics.

Instruments on MMS will measure charged particle velocities, as well as electric and magnetic fields, with unprecedentedly high (milliseconds) time resolution and accuracy.

MMS examines the microphysics of three fundamental space processes: magnetic reconnection, energetic particle acceleration, and turbulence. These processes occur universally in plasmas, the electrically conducting material that accounts for an estimated 99% of the observable universe made of positively and negatively charged particles.

MMS is the fourth mission of NASA’s Solar Terrestrial Probes (STP) Program. The goal of the STP Program is to understand the fundamental physical processes of the space environment from the sun to Earth, to other planets, and to the extremes of the solar system boundary.