A magnetic reconnection event observed by the MMS space probes

Artistic concept of the MMS space probes at the boundaries of the Earth's magnetic field (Image NASA/Goddard/Conceptual Image Lab)
Artistic concept of the MMS space probes at the boundaries of the Earth’s magnetic field (Image NASA/Goddard/Conceptual Image Lab)

An article published in the journal “Science” describes the first direct observation of the phenomenon called magnetic reconnection. NASA’s four MMS twin space probes allowed to obtain the best observations made so far of the interaction between the Earth and Sun’s magnetic fields. According to the researchers who analyzed the data collected, electrons trigger this phenomenon.

Magnetic reconnection’s effects are linked to various phenomena, also within the solar system. Giant eruptions on the Sun, radiation storms in space near Earth, cosmic particles that come from other galaxies were also observed in the solar system but those are the effects of a high-energy phenomenon. However, it was necessary to design a specific and very complex mission to observe magnetic reconnection directly.

In the past, various satellites observed particles that were accelerated but again those were the effects of magnetic reconnection. NASA compared these observations to those of debris thrown out by a tornado without actually seeing that phenomenon. The four MMS (Magnetospheric MultiScale) spacecraft, launched in March 2015, with their instruments and flying in a variable formation finally achieved the result hoped on October 16, 2015.

The observed magnetic reconnection lasted only a few seconds but those were enough for the 25 sensors on board of each of the four MMS probes to take thousands of detections. NASA and ESA’s Cluster II mission had already tried in the past to get that kind of results but the MMS spacecraft have much greater accuracy with the ability to get about thirty times more measurements in the same time.

This instrumental precision is the key to understanding the mysteries of magnetic reconnection such as the reason why it’s sometimes explosive, other times it’s steady and in some cases doesn’t take place at all. Another mystery was about the role of electrons and that’s where measurements accuracy and speed of the MMS space probes  already gave results.

In the event recorded by the MMS spacecraft, the flow of electrons moved along the magnetic field lines at the time of the interconnection between the Sun and the Earth’s fields. This movement generated an electromagnetic field which in turn generated an energy burst.

This is just the beginning because the MMS mission continues and the formation of the space probes is changed in time for optimum measurements. This will not only solve a scientific mystery but will provide a better understanding of space weather. These studies will help to understand other cosmic phenomena, including some that occur in the Earth’s magnetosphere and can affect the activities on Earth such as solar eruptions.

NASA created a video that describes the magnetic reconnection event observed by space probes MMS.

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