Scientists have discovered a strange new type of Martian aurora

We have new insight into a fascinating Martian phenomenon, thanks to a collaboration between two orbiting space probes.

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) and the United Arab Emirates’ Hope Probe have joined forces to study the ultraviolet aurora borealis that dance and glow high in the Martian atmosphere.

The new research reveals that these diurnal events are not always diffuse, featureless and evenly distributed, but are highly dynamic and variable, and contain minute structures.

“The observations of the EMM (Emirates Mars Exploration Mission) indicate that the auroras were so widespread and disorganized that the plasma environment around Mars must have been really turbulent, to the point that the solar wind was directly affecting the upper atmosphere wherever we observed auroral emission,” Scientist Planetary Mike Chavin of the University of Colorado Boulder.

“By combining EMM auroral observations with MAVEN measurements of the auroral plasma environment, we can confirm this hypothesis and determine that what we’re seeing was essentially a map of where the solar wind rains on the planet.”

Proton auroras – the most common auroras on the Red Planet – were first described in 2018, as seen in MAVEN data. They form somewhat similarly to how auroras form on Earth; However, since Mars is an entirely different beast, without an internally driven magnetosphere like Earth, the end result is unique to Mars.

The red planet closest to a global magnetic field is a flimsy planet caused by the slowing down of charged particles as they hit the atmosphere. Although weak, they are usually enough to deflect the many high-speed protons and neutrons raining down from the sun.

Proton auroras form when positively charged protons in the solar wind collide with Mars’ hydrogen shell and ionize, stealing electrons from hydrogen atoms to become neutral.

This charge exchange allows neutral particles to bypass the shock of the magnetic field around Mars, raining into the upper atmosphere and emitting ultraviolet light.

It was believed that this process reliably produced a uniform auroral emission over the course of Martian days. New notes show otherwise.

Rather than the expected smooth profile, data from the Hope probe shows that auroras are sometimes patchy, indicating that there could be unknown processes during the formation of these aurorae.

This is where Maven enters the picture. NASA’s orbiter carries a full suite of plasma instruments, to explore the solar wind, magnetic environment, and thermal ions in space around Mars.

He took measurements simultaneously while Hope photographed the strange auroras, and the collected data allowed scientists to reconstruct the reasoning behind it.

Diagram comparing the mechanisms of normal and incomplete proton aurora formation. (Emirates Mars Exploration Mission / Emirates Space Agency)

“By examining several observations of the UAE Mission on Mars of intermittent auroras of different shapes and locations, and combining these images with plasma measurements made by NASA’s Mars Atmosphere Mission and the EvolutioN volatile mission, we conclude that a number of processes can result in incomplete auroras. “. Write on their paper.

“This patchy aurora is mostly the result of plasma turbulence, which in some circumstances leads to direct precipitation of the solar wind over entire Martian days.”

In other words, the rare chaotic interaction between Mars and the solar wind is responsible for the patchy aurora. Although it is not entirely clear what the effect will be on the surface of Mars.

However, it is possible that there will be long-term effects on the atmosphere and water loss; Without a global magnetic field, Mars continues to lose both.

Interestingly, the proton auroras – whether smooth or patchy – could help us understand at least one of these, given that the hydrogen involved is created in part by water in the Martian atmosphere seeping into space.

The researchers wrote: “Several future data and modeling studies will be required to explore the full effects of these conditions on the evolution of the Martian atmosphere.”

The search was published in Geophysical Research Letters.

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