A Startling and Unexpected Event in the Martian Atmosphere: The Vanishing Solar Wind

Tuesday - December 12 2023, 23:05 UTC - 11 months ago

On Christmas 2022, a startling and unexpected event occured in the Martian atmosphere; the solar wind briefly vanished. MAVEN observed a dramatic drop in the stream of charged particles on Mars which caused major changes in the planet's atmosphere. Analysis revealed the cause of this event to be a stream interaction region of faster-moving solar wind overtaking slower-moving solar wind. This led to a cascade of effects, including the expansion of the Martian atmosphere and magnetosphere by thousands of kilometers, offering invaluable insights into the intricate dynamics of the Martian atmosphere.

A startling and unexpected event occurred in the Martian atmosphere in December 2022: the solar wind suddenly vanished for a brief period. On Christmas 2022, NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) mission spotted this unusual occurrence. Our colossal sun continuously spews a torrent of charged particles known as solar wind, which floods into outer space, impacting all the planets of our solar system.

However, the probe saw a dramatic drop in the stream of charged particles on Mars, which scientists found surprising. This episode caused a major change in Mars' atmosphere, including an increase in the extent of the magnetosphere. According to NASA, the spacecraft specializes in multiple observations, being able to "simultaneously observe both the Sun's activity and the response of the Martian atmosphere to these solar influences." .

"When we first saw the data, and how dramatic the drop in the solar wind was, it was almost unbelievable," said Jasper Halekas, professor at the University of Iowa and the lead author, in an official release. Halekas added: "We formed a working group to study the event, and we have found this time period to be rich with incredible findings." .

Furthermore, the lack of solar wind pressure led to the expansion of the Martian atmosphere and magnetosphere by thousands of kilometers. This expansion, observed in real-time by MAVEN, provides invaluable insights into the intricate dynamics of the Martian atmosphere.

What caused this event? Upon extensive analysis, the scientists discovered that this exceptional December 2022 solar event was caused by "faster-moving solar wind that overtook slower-moving solar wind." This type of solar interaction is called a stream interaction region. It typically causes a lack of solar wind, which is characterised by a 100-fold fall in density. The substantial reduction in solar wind density, by a factor of 100, triggered a cascade of effects on Mars. The planet's magnetosphere and ionosphere expanded by thousands of kilometers, exceeding thrice their normal size.

These findings are critical for understanding the mechanics regulating Martian atmospheric properties as well as water loss on Mars. "We are really getting to see how Mars responds when the solar wind is effectively removed," Halekas added. "It makes for a great outlier study on what Mars would be like if it were orbiting a less 'windy' star." .

This is the first time that MAVEN probe had observed this phenomenon, presenting an exceptional opportunity to deepen our understanding of the complex interplay between the Sun and the Martian atmosphere.