NASA’s Magnetospheric Multiscale Mission (MMS)

The NASA Magnetospheric Multiscale (MMS) mission was designed to study how the Sun’s and Earth’s magnetic fields connect and disconnect. This process is important at the Sun, other planets, black holes and everywhere in the universe and is a little-understood phenomenon known as magnetic reconnection.
To achieve this it would gather information about the microphysics of magnetic reconnection, energetic particle acceleration, and turbulence processes that occur in the magnetic field.
The science mission was split into two parts;
1. Firstly MMS will focus on the magnetic boundary between the Earth and the Sun, with an orbit of 2,550 by 70,080 km (1,580 by 43,550 mi).
2. The second part will study reconnection in Earth's magnetic tail with a more elliptical orbit of 2,550 by 152,900 km (1,580 by 95,010 mi).
During the science mission, the four MMS satellite constellation must maintain a tetrahedral formation while orbiting in their highly elliptical orbits in order to collect the desired science data.
Each of the four satellites have an octagonal shape that is approximately 3.5 meters wide and 1.2 meters high, with 8 wire booms protruding from them - four are 60 m (197 ft) long!
The MMS spacecraft were launched aboard a Delta II rocket and each weighed 1,360 kilograms (2,998 lbs) when launched.
The spacecraft are powered by small solar panels which will generate electricity to run the satellite.

Studying Earth's Magnetosphere