This artist’s rendition shows the four identical MMS spacecraft flying near the sun-facing boundary of Earth’s magnetic field (blue wavy lines). The MMS mission has revealed the clearest picture yet of the process of magnetic reconnection between the magnetic fields of Earth and the sun — a driving force behind space weather, solar flares and other energetic phenomena. Credit: NASA
A new study provides the first major results of NASA’s Magnetospheric Multiscale (MMS) mission. The paper describes the first direct and detailed observation of magnetic reconnection, which occurs when 2 opposing magnetic field lines break and reconnect with each other, releasing massive amounts of energy. The discovery is a major milestone in understanding magnetism and space weather.
Evidence suggests reconnection is a major driving force behind solar flares, coronal mass ejections (CMEs), magnetic storms, and auroras. Although researchers have tried to study reconnection in the lab and space for nearly half a century, MMS mission is the first to directly observe how reconnection happens. Flying in a pyramid formation at the edge of Earth’s magnetic field with as little as 10 km distance between 4 spacecraft, MMS images electrons within the pyramid once every 30 milliseconds. In contrast, MMS’ predecessor, Cluster II mission takes measurements every 3s -enough time for MMS to make 100 measurements.
Measuring the behavior of electrons in a reconnection event will enable a more accurate description of how reconnection works; in particular, whether it occurs in a neat and orderly process, or in a turbulent, stormlike swirl of energy and particles. It will also bring us one step closer to understanding space weather- including whether solar flares and magnetic storms follow any sort of predictable pattern like weather here on Earth. It will help us understand magnetars, which are neutron stars with an unusually strong magnetic field.
“Reconnection in Earth’s magnetic field is relatively low energy, but we can get a good sense of what is happening if we extrapolate to more energetic systems,” Swisdak added. “The edge of Earth’s magnetic field is an excellent test lab, as it’s just about the only place where we can fly a spacecraft directly through a region where reconnection occurs.”
To date, MMS has focused only on the sun-facing side of Earth’s magnetic field. In the future, the mission is slated to fly to the opposite side to investigate the teardrop-shaped tail of the magnetic field that faces away from the sun. http://umdrightnow.umd.edu/news/space-mission-first-observe-key-interaction-between-magnetic-fields-earth-and-sun
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