Researchers at the Institute of Geology and Geophysics, Chinese Academy of Sciences, revealed on the 26th that, based on observational data from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, they have conducted in-depth studies on the escape ion flow in the Martian magnetotail current sheet. For the first time, they have discovered that ions in the Martian atmosphere within the magnetotail current sheet sometimes exhibit high-energy, high-flux rapid escape phenomena. The relevant research findings have been published online in the journal "Geophysical Research Letters".
Mars, like Earth, boasts a diverse landscape with towering mountains, vast plains, and winding riverbeds, suggesting it might have been hospitable about 3.7 billion years ago. However, it has since transformed into a desolate planet with a thin, cold atmosphere.
Researchers believe solar wind plays a crucial role in the escape of Mars' atmosphere and water. The cessation of Mars' internal dynamo about 3.7 billion years ago resulted in the loss of its global magnetic field, leaving its atmosphere vulnerable to the impact of solar wind ions, which continuously erode atmospheric ions into space.
Through years of satellite observations, scientists have roughly understood the escape patterns of Martian atmospheric ions, identifying two main escape channels. However, there remains a lack of in-depth understanding regarding the specific escape processes and related physical phenomena.
In a recent study, researchers focused on the crucial region of Mars' magnetotail current sheets to delve deeper into the escape of Martian atmospheric ions. They discovered instances of high-speed tailward ion flows within these current sheets, primarily composed of heavy ions from the Martian atmosphere, with energies reaching approximately 1200 electron volts and tailward escape velocities of about 100 kilometers per second.
"These velocities significantly exceed our previous understanding. Previous studies suggested ion energies in Martian magnetotail current sheets generally do not exceed 50 electron volts, with tailward escape velocities of only 20 kilometers per second," explained researcher Rong Zhaojin. While these phenomena occur infrequently, they substantially enhance the escape of Martian atmospheric ions.
Rong Zhaojin noted that this research provides crucial factual evidence for understanding the physical processes of Martian atmospheric ion escape, deepening our understanding of Martian ion escape.
