Mars may once have been a habitable planet in its early history, instead of the cold, barren world that it is today. That may be because Mars' atmosphere has been leaking into space throughout the billions of years.
To understand why Mars lost its atmosphere, scientists set out to map electrical currents of Mars in the Martian atmosphere that might be responsible for letting the gas slip away.
Using NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, a team of researchers mapped the electrical current systems in the atmosphere of Mars. The outcome resulted in some psychedelic visualizations that helped scientists determine what drives the atmosphere to escape into space.
Blame the solar wind
The findings are detailed in a study published Monday, May 25 in the journal Nature Astronomy. The research suggests that the main driving force behind Red Planet's atmospheric escape is a solar wind, which continually flows from the Sun.
"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," Robin Ramstad, an experimental physicist at the University of Colorado, Boulder, and lead author of the new study, said in a statement.
Earth has a magnetic field, while Mars does not have one. Rather, charged particles released from the Sun's upper atmosphere, known as the solar wind, interact with the atmosphere of Mars and create an induced magnetosphere, or the area of space surrounding a planet.
The solar wind continually flows from the Sun at a speed of about one million miles per hour. Scientists are aware of the magnetosphere of Mars. They have yet to understand how it influences its atmosphere and how much energy is transferred from the solar wind, which would drive atmospheric escape.
The data shows the solar wind and magnetic field surrounding Mars, almost like throwing a handful of spaghetti noodles on someone's face.
Scientists used MAVEN's data to map the electrical currents around Mars in a second visualization. The image shows the electric currents that cupped the Red Planet's dayside and flowed into its night-side. Such electric-current loops link the upper atmosphere of Mars and its induced magnetosphere with the solar wind.
As the solar wind ions and electrons smash into the induced magnetic field of Mars, they are forced to flow apart because of their opposite electric charge. In contrast, some electrons flow in the other. This leads to the drape-like formation of the electrical currents around Mars from the dayside to the planet's night side.
Mars acts like a metal sphere
Meanwhile, the x-rays and ultraviolet radiation released by the Sun are continually ionizing regions of the upper atmosphere of Mars, rendering it capable of electrical conduction.
"Mars' atmosphere behaves a bit like a metal sphere closing an electric circuit," Ramstad said. That process is mainly responsible for the atmospheric escape of Mars.
The induced currents in the solar wind transform the solar wind 's energy into magnetic and electric fields that accelerate the charged particles of Mars' atmosphere. That causes the planet's atmosphere to leak into space.
Mars lost its atmosphere for billions of years without a magnetic field and transformed from a wet, warm, habitable world into a cold, dry desert.
In November 2013, MAVEN was launched to research the atmosphere, climate, and past habitability of the Red Planet.