Mercury’s magnetic field was “seen” by BepiColombo

In June 2023, the mission Baby Colombo The European Space Agency (ESA) and the Japanese Aerospace Agency (JAXA) carried out the operation Flyby of MercuryIt is the planet that will enter its orbit in the coming months. During the flyby, the probe observed a series of phenomena caused by… The planet’s magnetic fieldThey recorded it and sent it back to Earth, providing scientists with a preview of Mercury’s magnetic field and its properties, which BepiColombo will analyze in depth when it enters orbit around the planet in November 2026.

magnetic field. Scientists already know the properties Mercury’s magnetic field (It’s about 100 times less bright than Earth), but I’m still looking for answers about this intensity And to him Interactions. The magnetic field creates a “bubble” around Mercury called Magnetosphere Due to its proximity to the Sun, this magnetosphere is constantly bombarded by energetic particles ejected from the star’s surface.

A certain vision. when Baby Colombo It will permanently enter orbit around Mercury, He will break up In two separate spacecraft, the Mercury Planet Orbiter (MPO) commanded by the European Space Agency, and the Mercury Magnetospheric Orbiter (MMO) commanded by the Japan Aerospace Exploration Agency (JAXA). On two separate orbits. However, for now, the two spacecraft are still docked together, meaning their respective instruments can observe parts of Mercury that they would not be able to observe when they are in their own orbits.

Mercury’s magnetosphere. Using a series of instruments called BepiColombo’s Mercury Plasma Particle Experiment (MPPE), a group of scientists led by Lina Hadid, from the Laboratory of Plasma Physics at the Paris Observatory and co-principal investigator of the MPPE, has created an experimentA snapshot of Mercury’s magnetosphere. Hadid and her colleagues were able to collect data collected in about 30 minutes by BepiColombi, which was obtained during Flyby of Mercury Performed on June 19, 2023, it is the fourth of six Mercury flybys by the probe.

Confirmations and surprises. “These flights are fast; We passed Mercury’s magnetosphere in about 30 minutesIt passes from dusk to dawn and approaches only 235 kilometers from the planet’s surface. We sampled the type Particles are present“How hot it is and how it moves, which allowed us to clearly track the magnetic landscape over such a short period,” Hadid explained.

The researchers combined MPPE measurements with computer models to determine it All possible properties of the particles that make up the magnetosphere It was discovered by BepiColombo while flying.

“We saw structures along the boundary between the free-flowing solar wind and the magnetosphere, and we also crossed a region filled with extremely hot electrically charged gas (that’s plasma) that flows like a tail in the direction away from the Sun. We also got some surprises.” In fact, The researchers highlighted a region of turbulent plasma with a much wider range of energies than they had seen before on Mercury.

Unexpected electrical currents. In addition to these phenomena, Hadid also indicated the presence of “current loop“Any electrical current is carried by charged particles trapped in the planet’s magnetosphere, a few hundred kilometers from Mercury’s surface.

Earth also has a toroidal current in its magnetosphere, but it extends tens of thousands of kilometers from the surface, much further than Mercury’s atmosphere. Why these differences exist remains a mystery. “We noticed too Hot ions active near the equatorial plane and at low latitudes are trapped in the magnetosphere“We believe that the only way to explain this phenomenon is precisely through the circular current,” Hadid said.

Waiting to enter orbit. Hadid’s data allowed the BepiColombo teams to not only observe the planet’s magnetosphere; Understand how the probe interacts with the magnetosphere and surrounding space plasma. For example, when BepiColombo is heated by the Sun, the probe cannot detect colder, heavier ions because it is electrically charged, repelling the ions. However, when the probe is not heated by the Sun and is in Mercury’s shadow, a sea of ​​cold plasma ions covers the probe.

During a flyby in June 2023, BepiColombo detected ions Oxygen, sodium and potassium. These ions were likely emitted from the surface of Mercury The planet’s interactions with the solar wind or with micrometeor impacts on the surface. “It’s as if we suddenly see the surface texture ‘exploding’ in 3D through the planet’s very thin atmosphere, known as the exosphere,” Delcourt explains. This is just a glimpse of what analyzes the probe will receive once it enters orbit and after flying over the planet two more times: December 1, 2024 the ‘January 8, 2025.