BepiColombo Probe Discovers Universal Auroral Processes, Revealing Astonishing Findings on Mercury's Atmosphere

After investigating the overlooked innermost planet of the Solar System, the BepiColombo probe has unveiled the occurrence of auroral processes despite a virtually absent atmosphere.

Science Alert reported that the probe measured the electrons and ions on Mercury, which provided evidence of their acceleration. Detailed analysis revealed that these accelerated particles were a result of auroral processes linked to Mercury's magnetic field, resulting in the emission of faint X-rays.

All Planets in the Solar System Could Have an Aurora

The recent discovery of auroral processes on Mercury completes the observation of aurorae on every planet in the Solar System, challenging the conventional belief that these phenomena require both a magnetic field and an atmosphere.

The research, titled "Direct Evidence of Substorm-Related Impulsive Injections of Electrons at Mercury" published in Nature Communications, provides strong evidence supporting the acceleration of energetic electrons in Mercury's magnetosphere, their rapid drift towards the dawn sectors, followed by injection into the planetary nightside's closed magnetic field lines.

Astrophysicist Sae Aiwaza, the lead author of the study from the University of Pisa in Italy, said their findings indicate that the observed electron injections and subsequent drift, which occur throughout the Solar System, represent a universal mechanism for aurora generation.

This mechanism operates despite the distinct variations in the structure and dynamics of planetary magnetospheres. Conventionally, auroras were thought to require both a magnetic field and an atmosphere, with particles accelerated along magnetic field lines and interacting with atmospheric atoms and molecules to emit electromagnetic radiation.

Although the primary source of charged particles for an aurora is typically the solar wind, exceptions exist. As Science Alert reported, Jupiter's persistent aurora is predominantly fueled by electrons originating from its volcanic moon, Io.

More so, Saturn and Uranus's aurorae are powered by the solar wind. Voyager 2 detected auroral features on Neptune in 1989, but subsequent observations have been limited, leaving their characterization incomplete.

The surprises continue with Mars and Venus, planets previously considered unlikely to possess aurorae due to the absence of global magnetic fields. However, Mars displays localized auroral patches in its sky generated by magnetic patches on its surface.

Also, magnetic forces from the Sun are thought to contribute to the occurrence of atmospheric aurorae on Venus. These fascinating discoveries call into question our knowledge of the aurora generation and emphasize the intricacies of planetary magnetospheres and their interactions with charged particles.

BepiColombo Mission on Mercury

The joint endeavor between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) in the form of the BepiColombo probe, aims to study Mercury, as per Space.com. Launched in 2018, the spacecraft accomplished its first flyby of Mercury in 2021 and is set to enter orbit around the planet in 2025, making it the first mission with two satellites to a planet.

The findings revealed that within Mercury's magnetosphere, electrons with relatively low energy can undergo acceleration in the planet's dawn regions before being channeled into magnetic field lines on the night side.

Due to the planet's extremely thin atmosphere compared to Earth's, these accelerated electrons do not collide with the air. Rather, they smash with Mercury's surface, causing X-ray auroras to form.

According to astronomer Aizawa, despite the differences in the solar system's planets' characteristics, such as magnetic field strength and atmospheric composition, the mechanism by which electrons can be accelerated to generate auroras appears to be universal across these celestial bodies.

Check out more news and information on Space in Science Times.