NASA’s Magnetospheric Multiscale spacecraft — MMS — has discovered a new type of magnetic event that occurs around our planet. Magnetic reconnection is one of the most important processes that occur around the earth and this discovery has found reconnection where it has never been seen before in turbulent plasma. This discovery will help researchers understand space weather and could allow us to predict it in the future.
“In the plasma universe, there are two important phenomena: magnetic reconnection and turbulence,” said Tai Phan, a senior fellow at the University of California, Berkeley, and lead author on the paper. “This discovery bridges these two processes.”
Until this discovery magnetic reconnection was only thought to have occurred in the magnetosphere which surrounds the Earth but now thanks to MMS’s instruments magnetic reconnection has been observed in the larger magnetosheath and on much smaller scales.
MMS uses four identical spacecraft flying in a pyramid formation to study magnetic reconnection around Earth in three dimensions. Because the spacecraft fly incredibly close together — at an average separation of just four-and-a-half miles, they hold the record for closest separation of any multi-spacecraft formation — they are able to observe phenomena no one has seen before. Furthermore, MMS’s instruments are designed to capture data at speeds a hundred times faster than previous missions.
Even though the instruments aboard MMS are incredibly fast, they are still too slow to capture turbulent reconnection in action, which requires observing narrow layers of fast-moving particles hurled by the recoiling field lines. Compared to standard reconnection, in which broad jets of ions stream out from the site of reconnection, turbulent reconnection ejects narrow jets of electrons only a couple miles wide.
“The smoking gun evidence is to measure oppositely directed electron jets at the same time, and the four MMS spacecraft were lucky to corner the reconnection site and detect both jets”, said Jonathan Eastwood, a lecturer at Imperial College, London, and a co-author of the paper.
Crucially, MMS scientists were able to leverage the design of one instrument, the Fast Plasma Investigation, to create a technique to interpolate the data — essentially allowing them to read between the lines and gather extra data points — in order to resolve the jets.
“The key event of the paper happens in only 45 milliseconds. This would be one data point with the basic data,” said Amy Rager, a graduate student at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the scientist who developed the technique. “But instead we can get six to seven data points in that region with this method, allowing us to understand what is happening.”
With the new method, the MMS scientists are hopeful they can comb back through existing datasets to find more of these events, and potentially other unexpected discoveries as well.
Images Credits: NASA
