NASA | The MMS Mission's Unique Orbit

Scientist John Dorelli explains the MMS mission's orbit and why the four spacecraft fly in a tetrahedron formation. This complex arrangement enables scientists to gather data about magnetic reconnection in 3D.

On its journey, MMS will observe a little-understood, but universal phenomenon called magnetic reconnection, responsible for dramatic re-shaping of the magnetic environment near Earth, often sending intense amounts of energy and fast-moving particles off in a new direction. Not only is this a fundamental physical process that occurs throughout the universe, it is also one of the drivers of space weather events at Earth. Truly understanding the process requires four identical spacecraft to track how such reconnection events move across and through any given space.