Scientists Confirm Ongoing ‘Sputtering’ of Mars’ Atmosphere

For the first time, scientists have directly observed a key process driving the continuous loss of Mars’ atmosphere.

Decade-Long Research Leads to Discovery

After more than nine years of satellite data analysis, a team led by planetary scientist Shannon Curry from the University of Colorado Boulder has identified clear evidence of atmospheric sputtering.

According to the researchers, this discovery marks an essential step toward understanding how Mars lost much of its atmosphere and water over time.

“These results represent an important advance in observationally establishing sputtering’s role in the dissipation of Mars’ atmosphere,” the authors state in their paper, “and thus help better understand the history of water on the planet and the implications for its habitability through the ages.”

What is Atmospheric Sputtering?

Atmospheric sputtering is considered one of the dominant mechanisms for atmospheric loss in the early Solar System when the Sun was more active and emitted stronger radiation. This process happens when ions accelerated by the solar wind’s electric field collide with the atmosphere of bodies lacking a global magnetic field — such as Mars.

The effect is similar to a meteorite impact, which transfers energy to the surrounding medium and scatters particles. However, in sputtering, some atmospheric atoms and molecules gain enough energy to escape the planet’s gravity and are ejected into space.

Challenges in Observing Sputtering on Mars

Observing this phenomenon directly on Mars is extremely challenging. It requires simultaneous detection of the expelled neutral atoms and either the ions interacting with the atmosphere or the electric field accelerating them. It also demands measurements on both the dayside and nightside of the planet at high altitudes.

So far, only NASA’s MAVEN probe has the instruments and orbital configuration to make these observations. The team carefully examined data collected by the spacecraft since its arrival in Martian orbit in September 2014, searching for moments when the solar electric field coincided with a high concentration of argon in the upper atmosphere — a tracer element for this process.

Scientists found that above 350 kilometers altitude, argon density varies depending on the solar wind electric field’s direction, while at lower altitudes, this density remains stable.

Evidence Grows During Solar Storm Events

The analysis also showed that lighter argon isotopes escape more easily, leaving behind a higher concentration of heavier argon — a typical sign of active sputtering.Observations of a solar storm that reached Mars in January 2016 further supported this conclusion, as signs of the phenomenon became significantly stronger during that period.

The data not only support the conclusion that argon variations on Mars result from sputtering but also help understand conditions billions of years ago, when the Sun was younger and storms were more frequent.

“We find that the current atmospheric sputtering rate is more than four times higher than previous estimates and that solar storms can greatly intensify this process,” the researchers write.

Our results confirm that sputtering still occurs on Mars today and was likely the main mechanism for atmospheric loss during the early Solar System epochs when solar activity and extreme ultraviolet radiation were much stronger.

Read the original article on: Science Alert

Read more: Star Found Orbiting Within Another in Astonishing Cosmic First