In December 2023, scientists studying Mars data stumbled across something completely unexpected — observations of an atmospheric effect never before seen in the Red Planet’s atmosphere. Using instruments aboard NASA’s MAVEN mission, researchers identified a phenomenon previously known only from Earth’s magnetosphere, where charged particles are squeezed like toothpaste coming out of a tube along magnetic structures called flux tubes. This so-called Zwan-Wolf effect helps deflect the solar wind around Earth and has been observed there for decades. Now, a new study published in Nature Communications provides the first comprehensive observations of the same effect in Mars’ atmosphere.
The Zwan-Wolf effect reaches Mars
“When investigating the data, I all of a sudden noticed some very interesting wiggles,” said Christopher Fowler, a research assistant professor at West Virginia University and lead author of the study. “I would never have guessed it would be this effect, since it’s never been seen in a planetary atmosphere before.”
The Zwan-Wolf effect was first discovered in 1976 and, until now, had only been observed in planetary magnetospheres — not in atmospheres. Unlike Earth, Mars lacks a global magnetic field, which strongly influences how the planet interacts with the solar wind and space weather.
In the new study, scientists observed the Zwan-Wolf effect in the Martian ionosphere, deep within the atmosphere below 200 kilometers in altitude. This region contains large numbers of electrically charged particles. The data revealed that these particles were being compressed and redistributed throughout Mars’ atmosphere.
Solar storm helped scientists spot the phenomenon
Although Mars has what scientists call an induced magnetosphere — a magnetic field created by interactions between the solar wind and the Martian ionosphere — it can dramatically change in size and shape during powerful solar storms.
That is exactly what Fowler and his team observed in the MAVEN data when a major solar storm struck Mars. Based on the findings, the researchers believe the Zwan-Wolf effect may constantly occur in the Martian ionosphere but usually remains too weak for MAVEN’s instruments to detect. The intense space weather event likely amplified the effect enough for scientists to finally observe it clearly.
At first, the team noticed unusual fluctuations in magnetic field measurements as the spacecraft moved through the atmosphere. To investigate further, they analyzed observations from multiple MAVEN instruments, including measurements of charged particles in the ionosphere.
After ruling out several alternative explanations, the researchers concluded that the mysterious signatures could only be explained by the Zwan-Wolf effect.
“No one expected that this effect could even occur in the atmosphere,” said Fowler. “That’s what makes this even more exciting. It introduces interesting physics that we haven’t yet explored and a new way the Sun and space weather can change the dynamics in the Martian atmosphere.”
Why the discovery matters for future Mars research
Understanding the Zwan-Wolf effect on Mars could improve scientists’ knowledge of how space weather shapes the planet’s atmosphere. The discovery may also provide clues about similar processes on other worlds without strong magnetic fields, including Venus and Titan.
The findings also highlight how major solar storms can alter conditions around the Red Planet and potentially impact spacecraft and future missions operating near Mars.
“Knowing how space weather interacts with Mars is essential,” said Shannon Curry, principal investigator of MAVEN and research scientist at the Laboratory for Atmospheric Space Physics. “The MAVEN team continues making new discoveries with our datasets and finding these links between our host star and the Red Planet.”
MAVEN’s mission to study the Martian atmosphere
The MAVEN spacecraft launched in November 2013 and entered orbit around Mars in September 2014. The mission studies the planet’s upper atmosphere, ionosphere, and interactions with the Sun and solar wind to better understand how Mars gradually lost much of its atmosphere to space.
By studying atmospheric loss, scientists gain insight into the history of the Red Planet’s climate, the presence of ancient liquid water, and the planet’s past potential for habitability.
The spacecraft experienced a loss of signal with Earth-based ground stations on Dec. 6, 2025. In February 2026, NASA launched an anomaly review board to assess the spacecraft’s current condition and the possibility of restoring contact.
Source: NASA.
Image credit: LASP / CU Boulder.
Editor’s note: content may be edited for style and length.
