NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission studied the Red Planet's atmosphere for more than a decade. While contact was lost with the orbiter in December 2025, and the mission officially ended on June 3rd, the data it gathered continues to improve our understanding of Mars' atmosphere and the mechanics driving various phenomena. This includes Martian aurorae, which are similar to what people witness here on Earth, but with some notable differences.

In a recent study, a team led by researchers from the University of California, Berkeley, demonstrated that aurorae on Mars form in a way similar to those on Earth. Based on data obtained by several of MAVEN's scientific instruments, they found that the same mechanism that circulates charged solar particles from the Sun into Earth's atmosphere (the Dungey Cycle) also occurs on Mars. Owing to the differences in our two planets' magnetic fields, Martian aurorae occur on much smaller scales.

The paper describing their results, "Miniature Dungey-like cycle at Mars," appeared on July 23rd in the journal Nature Communications. The Dungey Cycle, named in honor of British space scientist James Dungey in 1961, describes the process that drives electrical currents in Earth's magnetic field, accelerates the charged solar particles that create auroras, and controls the circulation of plasma in Earthâs magnetosphere and upper atmosphere.

Mars, the red planet, has no magnetic field to protect it from the solar wind, meaning it loses its atmosphere in a way that Earth doesn't. Image credit: NASA/GSFC.

This process begins when the Sun's magnetic field lines get close to Earth's magnetosphere, where they reconnect and inject solar wind particles throughout Earth's magnetosphere and magnetotail. This leads to the firing of electrons back into Earth's atmosphere, which are channeled towards the poles to generate aurorae. Unlike Earth, Mars has no planet-wide magnetic field, only miniature magnetospheres that arise from intensely magnetized sections of crust scattered across the surface.

Earth's own field is generated by a dynamo action in the interior, where a molten outer core counter-rotates with Earth around a solid inner core. On Mars, geological activity in the core largely ceased about 4 billion years ago, causing its magnetic field to disappear. The magnetic regions are what is left from where lava cooled in the presence of this ancient field. The MAVEN mission has observed highly localized auroras over these fields, but it wasnât until now that scientists fully understood the physics behind their formation.

To create a full picture of the Dungey-like cycle on Mars, the team consulted data obtained by MAVEN's Magnetometer, Solar Wind Electron Analyzer (SWEA), and Suprathermal and Thermal Ion Composition (STATIC) instrument. These instruments were used to determine the configuration of Mars' magnetic fields, derive electrical currents, and measure plasma flows in the ionosphere, respectively.

Shaosui Xu, an associate research physicist at the Space Sciences Laboratory at UC Berkeley and the study's lead author, explained in a NASA press release:

We knew that magnetic reconnection was happening at Mars but did not expect it to be like the Dungey cycle. We really pushed the limit of STATIC to get the data we needed. It was the final piece to the puzzle in understanding these localized auroras. I remember in graduate school discussing with my advisor how the cycling of crustal magnetic fields could work at Mars. Itâs incredible to be part of the team that found the answer to that question.

A scientific visualization of the electric currents around Mars (blue and red arrows), showing how they envelop Mars in a nested, double-loop structure from its day side to its night side. Credits: NASA/Goddard/MAVEN/CU Boulder/SVS/Cindy Starr

The insight their work provides into what is happening within Mars' crustal magnetic fields addresses the question of how electrons are being energized to create auroras. By learning more about this process, scientists are also gaining a better understanding of how space weather interacts with the Red Planet as a whole, which is vital for future robotic and crewed missions. It lastly shows that a Dungey-like mechanism can happen on both large and small scales, providing clues about where else in the Solar System this process could be taking place.

Said Shannon Curry, MAVENâs principal investigator and a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder:

This is a remarkable result that changes how we think of Martian auroras and is another important step toward understanding why Mars and Earth have evolved so differently despite being governed by the same underlying physics. I am incredibly proud of our team's work on this discovery and excited to uncover new insights into the Red Planet and its evolution.

Further Reading: NASA, Nature Communications