Maven detects Martian atmospheric particle effect

NASA’s MAVEN orbiter has spotted a space-weather effect at Mars that, until now, had only been seen at Earth. NASA said the spacecraft detected the Zwan-Wolf effect in the Martian ionosphere, where charged particles were compressed and guided along magnetic structures called flux tubes. The agency published the update on May 18, and the underlying study appeared the same day in *Nature Communications*. The result matters because Mars does not have Earth’s kind of global magnetic shield. Instead, Mars has an induced magnetosphere created by the solar wind interacting with its upper atmosphere, and that environment can change substantially during solar storms. MAVEN was built to study exactly that interaction between the Sun and the Martian atmosphere. (science.nasa.gov) ### What exactly did MAVEN find? NASA said MAVEN identified the Zwan-Wolf effect, a process in which charged particles are squeezed along magnetic structures. At Earth, the effect is known from the magnetosphere and helps deflect the solar wind around the planet. At Mars, NASA said, the same process was seen operating in the atmosphere itself. (science.nasa.gov) The study described the Mars detection as the first observation of the Zwan-Wolf effect in the ionosphere of an unmagnetized planet lacking a strong dipole magnetic field. That makes the finding less about a single odd signal and more about a newly documented way Mars’ atmosphere can respond to solar forcing. ### Where in the Martian atmosphere did this happen? (science.nasa.gov) NASA said the effect was observed in the ionosphere below 200 kilometers above the surface, a region with large numbers of electrically charged particles. The data showed those particles being squeezed and redistributed around Mars’ atmosphere. (nature.com) That location is notable because the ionosphere sits deep enough in the atmosphere to connect space weather directly to atmospheric structure. In the paper’s summary, the authors said they showed the effect occurring in the ionosphere of Mars rather than only in a magnetosphere like Earth’s. ### Why did scientists only see it now? NASA said the signal turned up in data from December 2023, when scientists noticed unusual “wiggles” in magnetic-field measurements as MAVEN passed through the atmosphere. (science.nasa.gov) Christopher Fowler, a research assistant professor at West Virginia University and the study’s lead author, said he “would never have guessed” the signal was this effect because it had never been seen in a planetary atmosphere before. (nature.com) A large solar storm appears to have made the effect easier to detect. NASA said Fowler’s team thinks the Zwan-Wolf effect may be occurring constantly in the Martian ionosphere, but usually at levels too weak for MAVEN’s instruments to pick out clearly; the storm likely amplified it. That is NASA’s interpretation of the event based on the spacecraft data. (science.nasa.gov) ### How is Mars different from Earth here? Earth has a global magnetic field, while Mars does not. NASA said that difference changes how each planet interacts with the solar wind: at Earth the Zwan-Wolf effect is associated with the magnetosphere, while at Mars it was detected in an induced magnetic environment shaped by solar-wind conditions. (science.nasa.gov) The paper adds that Mars is an unmagnetized planet without a strong dipole field, which makes the detection scientifically unusual. In practical terms, the finding gives researchers another observed mechanism for tracing how solar storms can compress, reshape, and move charged material in the Martian upper atmosphere. That last point is an inference from the NASA release and the paper’s description of the phenomenon. (science.nasa.gov) ### What comes next for MAVEN researchers? The *Nature Communications* paper was published on May 18 with Fowler, Kathleen G. Hanley and Shannon Curry listed as authors. NASA said MAVEN’s mission is to understand the Martian upper atmosphere and how the planet lost much of it over time, so this result feeds directly into that broader effort. NASA’s mission page says MAVEN launched on Nov. 18, 2013, and entered Mars orbit on Sept. 21, 2014. (science.nasa.gov) The new Mars result now joins the mission’s longer record of observations on how the solar wind interacts with the planet’s atmosphere, with the paper and NASA’s May 18 mission update serving as the main public references for the finding. (science.nasa.gov) (nature.com)