(ORDO NEWS) — Thanks to the collaboration of two orbiting space probes, we have gained new insight into the amazing Martian phenomenon.
NASA‘s Mars Atmospheric and Volatile Evolution Probe (MAVEN) and the Hope probe from the United Arab Emirates have joined forces to study ultraviolet proton aurora that dance and glow high in the Martian atmosphere.
A new study shows that these daytime phenomena are not always diffuse, shapeless and evenly distributed, but are very dynamic and changeable, containing small-scale structures.
“EMM (Emirates Mars Mission) observations suggested that the aurora was so widespread and disorganized that the plasma environment around Mars must have been really disturbed, to the point that the solar wind had a direct effect on the upper atmosphere wherever we observed the auroral emissions,” says planetary scientist Mike Chaffin of the University of Colorado at Boulder.
“By combining EMM auroral observations with measurements of the MAVEN auroral plasma environment, we can confirm this hypothesis and determine that what we observed was, in fact, a map of where the solar wind hit the planet.”
Proton aurors – the most common auroras on the red planet – were first described in 2018, as seen in MAVEN data. They form quite similarly to how aurors form on Earth; however, since Mars is a very different beast, without an internally powered magnetosphere like Earth’s, the end result is unique to Mars.
The closest the red planet has to a global magnetic field is a weak one, caused by the buzzing of charged particles slowing down as they collide with the atmosphere. Weak, it is usually enough to deflect many of the high-speed protons and neutrons that fall from the Sun.
Proton aurora are formed when positively charged protons in the solar wind collide with the hydrogen shell of Mars and ionize, taking electrons from hydrogen atoms to become neutral.
This exchange of charges allows neutral particles to bypass the shock wave of the magnetic field around Mars, falling out in the upper atmosphere and emitting ultraviolet light.
It was believed that this process reliably provides uniform auroral radiation on the day side of Mars. New observations show the opposite.
Instead of the expected smooth profile, the data from the Nadezhda probe show that sometimes the aurora is scattered, suggesting that unknown processes may occur during the formation of these aurora.
This is where MAVEN comes into play. NASA’s orbiter is equipped with a complete array of plasma instruments to study the solar wind, magnetic environment, and thermal ions around Mars.
He simultaneously took measurements while the Hope took pictures of the strange aurora, and the combined data allowed scientists to reconstruct the cause of their occurrence.
By examining multiple Emirates Mars Mission observations of variegated aurors in various shapes and locations, and combining these images with plasma measurements from NASA’s Martian Atmosphere and Volatile Evolution mission, we have concluded that a number of processes can generate variegated aurors “, the researchers write in their paper.
“This speckled aurora is mainly the result of plasma turbulence, which under some circumstances leads to direct solar wind deposition all over the Martian dayside.”
In other words, a rare chaotic interaction between Mars and the solar wind is responsible for the speckled aurora; though it’s not entirely clear what effect this has on the Martian surface.
It is possible, however, that this has implications for the long-term loss of atmosphere and water; without a global magnetic field, Mars keeps losing both.
Interestingly, proton aurors both smooth and disjointed may help us understand at least one of these problems, since the hydrogen involved in them comes in part from water in the Martian atmosphere seeping into space.
“A lot of future data and modeling studies will be required,” the researchers write, “to elucidate the full implications of these conditions for the evolution of the Martian atmosphere.”
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