Map of electrical currents around Mars may explain its atmospheric loss

Hyperaxion May 28, 2020

Model created with Maven spacecraft data reveals why the Red Planet does not have an Earth-like atmosphere.

Data obtained by the Maven spacecraft (Mars Atmosphere and Volatile Evolution), launched in 2013 by NASA, helped scientists to create a map of the systems of electric currents around Mars. According to the article published by the team in the journal Nature Astronomy, on Monday (25), the model suggests that the Red Planet has lost its atmosphere precisely because of its electricity.

Map of electrical currents around Mars may explain its atmospheric loss
(Credit: NASA/Goddard/MAVEN/CU Boulder/SVS/Cindy Starr).

“These currents play a fundamental role in the atmospheric loss that transformed Mars from a world that could have supported life into an inhospitable desert,” said Robin Ramstad, the article’s lead author, in a statement.

In the Earth’s core, molten iron flows under the crust, creating our planet’s magnetic field and, consequently, generating electrical currents. Since Mars is a rocky planet like ours, it can be assumed that the same is true there. But this is not the case: the Red Planet does not generate a magnetic field by itself.

What happens on Mars?

The solar wind, formed largely by electrons and electrically charged protons, blows constantly from the Sun, at about a million kilometers per hour, and interacts with the objects in our Solar System. The solar wind is also magnetized, however, its magnetic field does not easily penetrate the upper atmosphere of non-magnetized planets, as is the case with Mars.

In this way, the currents induced in the ionosphere of Mars (upper part of the Martian ‘atmosphere’) cause an accumulation and a strengthening of the planet’s magnetic field, creating the so-called induced magnetosphere.

(Credit: NASA/Goddard/MAVEN/CU Boulder/SVS).

According to scientists, when ions and electrons from the solar wind hit this induced magnetic field, these particles are forced to separate due to the opposite electrical charge. As a result, ions flow in one direction and electrons in the other, forming electrical currents that circulate from one side of Mars to the other.

At the same time, solar x-rays and ultraviolet radiation constantly ionize part of the upper atmosphere of the Red Planet, transforming it into a combination of electrically charged electrons and ions that can conduct electricity. “Mars’ atmosphere behaves a bit like a metal sphere closing an electric circuit,” explained Ramstad. “The currents flow in the upper atmosphere, with the strongest current layers persisting at 120-200 kilometers (about 75-125 miles) above the planet’s surface.”

Mars atmosphere

Without a global magnetic field around Mars, currents induced by the solar wind can form a direct electrical connection to the planet’s upper atmosphere. This process, in turn, transforms the energy of the solar winds into electric and magnetic fields that accelerate charged atmospheric particles in that area, which enables the “escape” of these atoms into space and makes the existence of an atmosphere like Earth’s unfeasible.

The atmospheric loss caused by solar winds that hit Mars billions of years ago contributed to the transformation of the planet into a cold desert. Now, the team plans to continue studying this process to find out more about the Red Planet. “We are now currently working on using the currents to determine the precise amount of energy that is drawn from the solar wind and powers atmospheric escape,” noted Ramstad.

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