As dry and flaky the Martian surface looks, this was not always the case. Several studies have been conducted up till now that prove that the Martian atmosphere was once warm and humid enough to support life. Several sedimentary deposits have been found that prove the existence of water at some point in the Martian history.
Astrophysicists have believed that the red planet was stripped of its atmosphere owing to solar winds. Flowing from the sun, solar winds are composed of charged particles. However, there was no such direct proof for this theory up till now.
A team of researchers decided to study the electric current systems in Mars’ atmosphere using the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. It was known that the charged particles inside the solar winds created an induced magnetosphere around the planet, in the absence of a magnetic field. However, the way that magnetosphere influenced the Martian atmosphere was still unknown. Hence, the scientists set out mapping the electric currents around Mars.
The images from MAVEN showed that Mars’ upper atmosphere and its induced magnetosphere were connected to the solar winds via these electric currents.
As the charged particles come in contact with Mars’ induced magnetic field, they split off in different directions owing to their different charges. This explained the shape of electric currents around Mars. This was not it, but the x-rays and ultraviolet radiation were known to be ionizing Mars’ upper atmosphere, enabling it to conduct electricity.
Hence, it was known that solar winds result in electric and magnetic fields around Mars, causing the planet to lose its atmosphere and transform into a desert. Things could have been different if Mars had a magnetic field, but unlike Earth, it does not have one and has been losing its atmosphere for billions of years.
Journal reference: https://doi.org/10.1038/s41550-020-1099-y