Space might look like a sprawling, inky abyss, but invisible to the human eye is a wealth of magnetic activity.
Earth has a magnetic field called the magnetosphere, which is frequently buffeted by solar winds exuded by the Sun. These winds carry their own magnetic field and produce what scientists call a “magnetic reconnection” high above the Earth’s surface. In March 2015, NASA launched four spacecraft, known as MMS, so they could travel through the magnetosphere and record these reactions. Now, scientists have published their initial observations in the journal Science.
Recordings from a flyby in October 2015 show that when two magnetic fields collide, electrons shoot out from the point of impact in straight lines, speeding through the magnetic boundaries that would normally contain them. Once free, they slowly begin to curve and ultimately perform a U-turn in response to the new magnetic fields they encounter.
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The quality of the data collected by MMS is unprecedented. Scientists have used satellites before to observe this phenomena, but as NASA explains, it was “like seeing debris flung out from a tornado, but never seeing the storm itself.” With MMS, researchers can sail into the heart of the storm.
“The decades-old mystery is what do the electrons do, and how do the two magnetic fields interconnect,” Jim Burch, lead author of the Science paper and principal investigator for MMS at the Southwest Research Institute in San Antonio said. “Satellite measurements of electrons have been too slow by a factor of 100 to sample the magnetic reconnection region. The precision and speed of the MMS measurements, however, opened up a new window on the universe, a new ‘microscope’ to see reconnection.”
Magnetic reconnection converts magnetic energy into kinetic or thermal energy. It’s important to understand this phenomenon because it influences the “space weather” found in the Earth’s magnetosphere. Here, humanity operates a range of satellites which are occasionally disrupted by these intense reactions. MMS observations will allow NASA to improve its predictions for magnetic reconnection and, as a result, better control its equipment in space. Magnetic fields are present in other parts of the universe too, so dissecting these reactions — a prime driver of space radiation — could also protect our astronauts on risky missions.