In a first for a planet without a global magnetic field, scientists have detected a space weather phenomenon known as the Zwan-Wolf effect in the ionosphere of Mars.
December 2023 — Researchers using data from NASA's MAVEN mission have identified the Zwan-Wolf effect in the Martian ionosphere. This phenomenon, previously only observed in planetary magnetospheres, involves charged particles being squeezed along magnetic flux tubes.
Key Details
- First described in 1976, the Zwan-Wolf effect has been studied at Earth for decades but had never before been detected on an unmagnetized world.
- Mars lacks a global magnetic field. Unlike Earth, its ionosphere interacts with the solar wind via an induced magnetosphere.
- The effect was detected during a large solar storm, which amplified it to detectable levels. It may occur constantly but at lower intensities.
- The study was published in Nature Communications, led by Christopher Fowler of West Virginia University.
"This phenomenon, previously only observed in planetary magnetospheres, involves charged particles being squeezed along magnetic flux tubes."
Observations
MAVEN instruments measured magnetic field fluctuations and charged particle behavior in the Martian atmosphere below 200 km altitude. The features matched the Zwan-Wolf effect, ruling out other explanations.
Implications
Understanding this effect at Mars helps explain how space weather affects unmagnetized bodies like Venus and Saturn's moon Titan. It also provides insight into Martian atmospheric loss, which is directly relevant to the planet's climate history and potential habitability.
"This finding helps explain how space weather affects unmagnetized bodies like Venus and Saturn's moon Titan."
Mission Context
MAVEN entered Mars orbit in September 2014 to study the upper atmosphere and solar wind interactions. However, on December 6, 2025, the spacecraft lost contact with Earth. NASA launched an anomaly review board in February 2026 to investigate the loss of communication.