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MMS Key Messages

MMS solves the mystery of how magnetic fields around Earth connect and disconnect, explosively releasing energy via a process known as magnetic reconnection. MMS consists of four identical spacecraft that will provide the first three-dimensional views of this fundamental process that occurs throughout our universe.

Like stretched rubber bands, magnetic fields store energy that is released explosively when the field lines are broken during reconnection. Unlike rubber bands, reconnection can drive particles to nearly the speed of light.

MMS uses Earth's protective magnetic space environment, the magnetosphere, as a natural laboratory to directly observe how it interacts with the sun's extended magnetic field, which can result in reconnection.

The four MMS spacecraft fly in varying formations through reconnection regions in well under a second, so key sensors on each MMS spacecraft have been designed to take certain measurements of the space environment 100 times faster than any previous mission.

MMS Key Sub-Messages


MMS spacecraft will fly in an adjustable pyramid formation, to determine the size and structure of reconnection regions.

MMS will travel through areas near Earth where conditions for magnetic reconnection are known to exist, studying the unique reconnection characteristics of both the dayside and nightside of Earth.

Magnetic reconnection is one of the most important drivers of space weather events. Eruptive solar flares, coronal mass ejections, and geomagnetic storms all involve the release, through reconnection, of energy stored in magnetic fields. Space weather events can affect modern technological systems such as communications networks, GPS navigation, and electrical power grids.

Reconnection can be observed and studied in the laboratory where it can also interfere with sustainable energy generation in fusion devices.

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