In August 2021, ESA/JAXA BepiColombo spacecraft bound for Mercury Performed a second flyby of Venus, providing short-term observations of its guided magnetosphere. The spacecraft detected cold oxygen and carbon ions at a distance of about six planet radii, in an area of the magnetosphere that has never been explored before.
Schematic illustration of planetary material escaping through the sides of Venus's magnetic sheath. The red line and arrow indicate the observation region and direction of BepiColombo as the ions escape (C+,oh+,H+) was observed. Image credit: Thibaut Roger / Europlanet 2024 RI / Hadid other.
Venus was similar to Earth in many ways during its formation, including the presence of large amounts of liquid water.
However, Venus eventually underwent a divergent evolution, leading to major differences between the two planets.
Unlike Earth, Venus is currently a very dry planet with no inherent magnetic field.
The continuous influence of the solar wind on the atmospheres of both planets results in significant atmospheric losses.
Venus' atmosphere is primarily composed of carbon dioxide and small amounts of nitrogen and other trace species, and is affected by interactions with the solar wind, leading to significant ion fluxes.
“This is the first time that positively charged carbon ions have been observed to be ejected from Venus's atmosphere,” said Dr. Lina Hadid, a researcher at the Plasma Physics Institute and CNRS.
“These are heavy ions that typically move slowly, so we're still trying to understand the mechanism.”
“An electrostatic 'wind' may be moving them away from Earth, or they may be accelerated by centrifugal action.”
“Unlike Earth, Venus does not generate an intrinsic magnetic field at its core.”
“Nevertheless, interactions between charged particles emitted by the sun (solar wind) and charged particles in Venus' upper atmosphere create a weak, comet-shaped 'induced magnetosphere' around the planet. ”
“Around the magnetosphere there is a region called the 'magnetic sheath' where the solar wind is slowed down and heated.”
On August 10, 2021, BepiColombo passed Venus to slow down and adjust its course towards its final destination, Mercury.
The probe soared up the long tail of the planet's magnetic sheath, emerging from the nose of the magnetic region closest to the sun.
Over a 90-minute observation period, BepiColombo's mass spectrometer (MSA) and mercury ion analyzer (MIA) will measure the number and mass of charged particles encountered, and detect chemical and Captured information about physical processes. magneto sheath.
“Characterizing the loss of heavy ions on Venus and understanding the escape mechanisms will help us understand how Venus's atmosphere evolved,” said Dr. Dominique Delcourt, principal investigator at MSA and researcher at the Plasma Physics Institute. “This is critical to understanding how water is lost.” .
“This result shows a unique result from measurements made during a flyby of a planet, in which the spacecraft may pass through areas that are generally inaccessible to orbiting spacecraft. '' said Dr. Nicolas Andre, a researcher at the Astrophysical and Planetary Institute.
of study It was published in the magazine natural astronomy.
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LZ Hadid other. BepiColombo's observations of cold oxygen and carbon ions on the side of Venus' induced magnetosphere. Nat Astron, published online on April 12, 2024. doi: 10.1038/s41550-024-02247-2
Source: www.sci.news
