Using five years of magnetic field data obtained by NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft, a team of scientists has created the first-ever map of the electric current systems in the Martian induced magnetosphere. Theirresultsappear in the journalNature Astronomy.
Earth’s magnetism comes from its core, where molten, electrically conducting iron flows beneath the crust. Its magnetic field is global, meaning it surrounds the entire planet.
Since Mars is a rocky planet like Earth, one might assume that the same kind of magnetic paradigm functions there, too. However, the Red Planet doesn’t generate a magnetic field on its own, outside of relatively small patches of magnetized crust.
Something different from what we observe on Earth is happening on Mars.
The solar wind blows constantly from the Sun and interacts with the objects in the Solar System.
It is also magnetized and this magnetic field cannot easily penetrate the upper atmosphere of non-magnetized planets like Mars.
Instead, currents that it induces in the planet’s ionosphere cause a pile-up and strengthening of the magnetic field, creating a so-called induced magnetosphere. How the solar wind powers this induced magnetosphere at Mars has not been well understood until now.
As solar wind ions and electrons smash into this stronger induced magnetic field near Mars, they are forced to flow apart due to their opposite electric charge. Some ions flow in one direction, some electrons in the other direction, forming electric currents that drape around from the dayside to the nightside of the planet.
At the same time, solar X-rays and ultraviolet radiation constantly ionize some of the upper atmosphere on Mars, turning it into a combination of electrons and electrically charged ions that can conduct electricity.
“Mars’ atmosphere behaves a bit like a metal sphere closing an electric circuit,” said Dr. Robin Ramstad, a physicist in the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.
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