Summary
By the end of this article, you will understand exactly how extreme solar storms from space and massive dust storms from the surface battle for control of the Martian atmosphere.
Quick Facts
Surprise: Solar flares can penetrate all the way down to 80 km above the Martian surface.
Salient Idea: Dust storms heat the lower atmosphere, causing the entire upper atmosphere to literally swell and 'loft' upwards into space.
Surprise: Extreme solar wind acts like a giant hand, physically suppressing and crushing the rising atmosphere back down.
Surprise: The collision of these dust and solar storms triggers glowing proton auroras across the Martian day side.
The Discovery: Attacked from Above and Below
In 2021 and 2022, scientists using the MAVEN spacecraft set out to observe the Martian ionosphere—the electrified edge of space. They analyzed data from two distinct, extreme periods. First, an intense solar storm hit Mars in April 2021. Then, in June 2022, a massive, overlapping A-class and B-class dust storm choked the planet just as another wave of solar storms arrived. They found a Surprise: the dust storms were heating the planet, causing the atmosphere to expand and ‘loft’ upwards by up to 20 kilometers as a single unit. But simultaneously, the immense dynamic pressure from the solar wind was slamming into that expanded atmosphere, suppressing the loft and violently stripping away its particles. Mars was caught in a planetary-scale vise grip.
The thermosphere, on average, lofts as a unit… demonstrating the widespread and multifaceted impact of dust activity and extreme solar activity.
— Marianna Felici et al.
The Science Explained Simply
This is NOT the breathable layer of air where weather happens on Earth. The ionosphere is a high-altitude layer of gas that has been cooked by the sun’s ultraviolet light and X-rays until the electrons are ripped away from their atoms, creating a sea of charged particles called plasma. The Salient Idea here is the concept of ‘Total Electron Content’ (TEC). When a solar storm (like a Coronal Mass Ejection) hits Mars, it injects extreme energy into this plasma layer, spiking the TEC by up to 200%. But unlike Earth, Mars has no thick atmospheric cushion. The high-energy solar particles can penetrate incredibly deep—down to 80 km above the surface—forcing the ionosphere to dramatically reshape itself in real-time.
The Aurora Connection
Earth’s strong magnetic field deflects the solar wind, funneling it to the poles to create our beautiful Northern Lights. Mars lost its global magnetic shield billions of years ago. When the expanding, dust-choked Martian atmosphere collides with an aggressive solar storm, the solar wind plows directly into the planet’s swollen halo of hydrogen gas. This direct impact creates highly active proton auroras that can span the entire day side of the planet. Studying how these auroras flare up during dust storms gives us a terrifyingly clear picture of how unprotected planets bleed their atmospheres out into the cold void of space.
Numerous proton aurora events observed during this time period correspond with increases in the ROSE TEC… demonstrating widespread impact.
— MAVEN Research Team
A Peek Inside the Research
How do you measure a completely invisible layer of plasma from orbit? The researchers didn’t use cameras; they used Radio Occultation. By transmitting a radio signal from the MAVEN spacecraft straight through the Martian atmosphere to receivers on Earth, scientists measured exactly how much the radio waves bent and delayed. This delay reveals the exact density of electrons at every altitude. To prove the solar and dust storms were changing the planet, the team first had to build a meticulous mathematical model of a ‘quiet’, undisturbed Mars. By subtracting this baseline from their storm data, the invisible effects of the cosmic tug-of-war suddenly became crystal clear.
To quantify the effects that space weather events and dust storm induce, we need to isolate and subtract the baseline photochemically produced ionosphere first.
— Marianna Felici et al.
Key Takeaways
The ionosphere of Mars is highly dynamic and controlled by both space weather and surface weather.
MAVEN uses radio waves passing through the atmosphere to measure the exact thickness and electron density of Mars.
Solar energetic particles strip electrons from molecules, creating dense layers of plasma deep in the atmosphere.
A planet's lack of a global magnetic field leaves its atmosphere entirely at the mercy of the Sun.
Sources & Further Reading
Frequently Asked Questions
Q: Does Mars have a magnetic field like Earth?
A: No. Mars lost its global magnetic field billions of years ago. It only has weak, localized magnetic ‘umbrellas’ in its crust, leaving the majority of the planet’s atmosphere exposed to the direct blast of the solar wind.
Q: What happens to the atmosphere when it ‘lofts’?
A: When a dust storm heats the lower atmosphere, the gas expands and rises to higher altitudes. This pushes the upper atmosphere further out into space, where it is easier for solar winds to strip it away.
Q: Can we see Martian auroras with our naked eyes?
A: Unlike Earth’s vibrant green and pink auroras, Martian proton auroras happen in the ultraviolet spectrum, meaning they are completely invisible to human eyes but shine brightly to specialized instruments like MAVEN’s imaging spectrograph.
