The MMS spacecraft offers for the first time an elusive energy explosion view

Artistic representation of the MMS spacecraft that provided the first insight into magnetic reconnection. Credit: NASA / GSFC

Researchers at the University of New Hampshire have captured a singular event difficult to see involving a "magnetic reconnection" – the process by which rare particles and energy around the Earth collide, producing an explosion fast but powerful – in the magnetotail of the Earth, the magnetic environment trails behind the planet.

Magnetic reconnection has remained a mystery to scientists. They know that this exists and have documented the potential effects of energy explosions – causing auroras and possibly havoc on power grids in the case of extremely important events – but they have not fully understood the details. In a study published in the journal Science, scientists describe for the first time the main details of the operation of this process of energy conversion in the magnetotail of the Earth.

During its second phase, NASA's Multi-Scatter Magnetospheric Mission (MMS) observes the magnetic reconnection in action behind the Earth, as shown by the intertwined blue and red magnetic field lines. Credit: Patricia Reiff / NASA Goddard / Joy Ng

On the terrestrial side, magnetic reconnection is asymmetrical, which means that it throws particles, such as ions and electrons, in different directions. In this simulation, the particles mainly move away from the reconnection site along the black magnetic field lines. Credit: Paul Cassak / NASA Goddard / Joy Ng

"It was a remarkable event," said Roy Torbert of the Space Science Center at UNH and Deputy Chief Investigator of the Magnetospheric Multiscale Mission, or MMS of NASA. "We have known for a long time that this happens under two types of regimes: asymmetric and symmetrical, but this is the first time we have seen a symmetric process."

Magnetic reconnection occurs every day around the Earth due to the twisting and reconnection of magnetic field lines. This occurs in different ways in different places, with different effects. Highly ionized gas particles, called plasmas, can be converted to produce a single, powerful, split – second explosion that can cause powerful electron currents to fly off at supersonic speeds. The sight, which was detected as part of the scientists' work on the MMS mission, had sufficient resolution to reveal its differences from other reconnection regimes around the planet, such as the asymmetrical process observed in the magnetopause around the Earth, closer to the sun.

"It's important because the more we know and understand about these reconnections," said Torbert, "the more we can prepare for extreme events through reconnects around the Earth or elsewhere in the universe."

Magnetic reconnection also occurs on the sun and across the universe – in any case, driving the particles with force and causing much of the change observed in dynamic space environments – getting to know it around the Earth also helps us understand reconnection to other places in the universe. can not be reached by a spaceship. The more we understand the different types of magnetic reconnection, the more we can understand what these explosions might look like elsewhere.

Behind the Earth, far from the Moon, a magnetic reconnection occurs symmetrically. This simulation shows particles moving away from the reconnection site equally in both directions, confined by the red magnetic field lines. Credit: Michael Hesse / NASA Goddard / Joy Ng

For the first asymmetric event reported on October 16, 2015 and now this symmetrical event of July 11, 2017, NASA's MMS mission made history by flying over magnetic reconnection events close to Earth. The four MMS spacecraft launched from a single rocket have only been a few seconds inside the events, but the instruments that the UNH researchers have helped to develop have have been able to collect data at an unprecedented rate a hundred times faster than ever before. Thus, for the first time, scientists have been able to track the evolution of magnetic fields, the appearance of new electric fields, as well as the speed and direction of different charged particles.

This work was funded by NASA, the National Aeronautics and Space Administration.

Publication: R. B. Torbert, et al., "Electron Scale Dynamics of the Diffusion Region in Symmetric Magnetic Reconnection in Space", Science Nov. 15, 2018: eaat2998; DOI: 10.1126 / science.aat2998