In a first, scientists have directly observed magnetic reconnection, a fundamental process in nature that may be key to learning more about the cosmos and help protect future deep space missions as we journey farther from our planet.
When two sets of magnetic fields connect, an explosive reaction occurs. As the magnetic fields realign and snap into a new formation, they send particles zooming off in jets.
The effects of this sudden release of particles and energy — such as giant eruptions on the Sun, the aurora, radiation storms in near-Earth space, high energy cosmic particles that come from other galaxies — have been observed throughout the solar system and beyond. However, scientists have never been able to witness the phenomenon of magnetic reconnection directly.
“We developed a mission, the Magnetospheric Multiscale mission (MMS), that for the first time would have the precision needed to gather observations in the heart of magnetic reconnection,” said Jim Burch, principal investigator for MMS at the Southwest Research Institute in the U.S.
“By seeing magnetic reconnection in action, we have observed one of the fundamental forces of nature,” said Mr. Branch.
MMS is made of four identical spacecraft that NASA launched in March last year. They fly in a pyramid formation to create a full 3D map of any phenomena they observe.
In October last year, the spacecraft travelled through a magnetic reconnection event at the boundary where Earth’s magnetic field bumps up against the Sun’s magnetic field.
In only a few seconds, the 25 sensors on each of the spacecraft collected thousands of observations.
This unprecedented time cadence opened the door for scientists to track better than ever before how the magnetic and electric fields changed, as well as the speeds and direction of the various charged particles.
Any set of magnetic fields can be thought of as a row of lines. These field lines are always anchored to some body — a planet, a star — creating a giant magnetic network surrounding it. It is at the boundaries of two such networks where magnetic reconnection happens.
If the two sets of field lines point in opposite directions, the process of realigning is dramatic.
“One of the mysteries of magnetic reconnection is why it’s explosive in some cases, steady in others, and in some cases, magnetic reconnection doesn’t occur at all,” said Tom Moore, from the NASA’s Goddard Space Flight Centre in the U.S.
The observations show that the electrons shot away in straight lines from the original event at hundreds of miles per second, crossing the magnetic boundaries that would normally deflect them.
Once across the boundary, the particles curved back around in response to the new magnetic fields they encountered, making a U-turn.