NASA spacecraft detects rare substorm at Earth’s magnetic tail

Something unusually strange is happening in the tail of Earth’s magnetic field: the magnetotail.

Researchers at the Southwest Research Institute (SwRI) examined data collected by NASA’s Magnetospheric Multiscale (MMS) mission to solve a long-standing mystery surrounding “substorms.”

The magnetotail is an extended part of the Earth’s magnetosphere that moves away from the Sun. The tail is formed by the influence of the Earth’s magnetic field and the solar wind.

This means that the magnetotail is littered with energetic particles, which can occasionally be ejected by a tumultuous event called a magnetospheric substorm.

In 2015, NASA launched this MMS mission specifically to study this magnetic region up close and decipher how the Sun’s and Earth’s magnetic fields reconnect. Magnetic reconnection occurs when lines in a magnetic field come together, separate, and then reconnect.

Unusual case of magnetic reconnection without the substorm

The MMS spacecraft examined this region looking for signs of magnetic reconnection, which produces substorms. In 2017, MMS made an unexpected discovery: evidence of magnetic reconnection without the associated substorm.

Extreme electric currents and magnetic field variations in the magnetic tail are important indicators of a substorm, but MMS data has shown no such signs.

In this one-year project, the SwRI will compare MMS data with reconstructions of the global magnetosphere to unlock the secrets of this mysterious phenomenon.

“We want to see how the local physics observed by MMS affects the entire global magnetosphere,” says Andy Marshall, a postdoctoral researcher at SwRI.

“By comparing that event to more typical substorms, we aim to improve our understanding of what causes a substorm and the relationship between substorms and reconnection,” Marshall added.

The Community Coordinated Modeling Center at NASA’s Goddard Space Flight Center will use the University of Michigan’s Space Weather Modeling Framework to develop reconstructions of the global magnetosphere.

Marshall further explained: “It is possible that significant differences exist between the global magnetotail convection patterns for substorms and the tail reconnection of non-substorms. We did not look at the movement of the magnetic field lines on a global scale, so it could be that this unusual substorm was a very localized event that MMS happened to observe.”

“If not, this could reshape our understanding of the relationship between tailside reconnection and substorms.”

Substorms are important in space weather monitoring

MMS consists of four identical spacecraft and is part of NASA’s Solar Terrestrial Probes Program mission. It was built by NASA’s Goddard Space Flight Center.

Since launch, the MMS spacecraft has been investigating the magnetopause, the boundary between Earth’s magnetic field and the solar wind.

According to the press release, the complex substorms are essential to study because they are a type of space weather that produces stunning auroral displays.

However, as mentioned above, substorms also lead to significant electrical activity in space.

The strong currents can cause geomagnetic disturbances, which can disrupt and possibly destroy power distribution networks, electrical systems and even space-based infrastructure such as satellites.

Hopefully, this new project will be able to decipher the underlying mechanisms responsible for this unusual substorm.


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Mrigakshi Dixit Mrigakshi is a science journalist who enjoys writing about space exploration, biology and technological innovations. Her professional experience spans both television and digital media, allowing her to learn a variety of storytelling formats. Her work has been featured in well-known publications including Nature India, Supercluster and Astronomy magazine. If you have any pitches in mind, don’t hesitate to email her.

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