NASA’s Magnetic Multiscale mission, or MMS, consists of a fleet of four identical satellites studies three phenomena in Earth’s magnetosphere: magnetic reconnection, energetic particle acceleration, and turbulence.
These processes occur everywhere in the universe but can only be effectively studied close to Earth.
Magnetic reconnection happens when lines of magnetic force cross, cancel and reconnect.
This releases magnetic energy in the form of heat and charged particles, causing solar flares on the sun and magnetic storms and auroras on Earth.
Each satellite spins at 3 rotations per minute while doing science observations. Deployable booms extend out as much as 197 feet (60 meters) from the spacecraft, each carrying electric-field sensors or magnetometers.
Source SPACE.com: All about our solar system, outer space and exploration
Source: http://www.space.com/28778-nasa-mms-satellites-magnetic-fields-infographic.html