Czech Scientists Record Electrical Discharge on Mars Resembling Terrestrial Lightning

Czech scientists have demonstrated that electrical discharges similar to lightning occur in the Martian atmosphere. A four-member research team from the Faculty of Mathematics and Physics at Charles University and the Institute of Atmospheric Physics of the Czech Academy of Sciences achieved this based on measurements from the NASA MAVEN orbiter. MAVEN has been orbiting Mars since 2014, providing open data to the scientific community.

Unlike Earth, Mars lacks a global magnetic field, possessing only local fields created by magnetized material in the planet's crust. Its atmosphere is thin, and lightning there does not originate in water clouds, but rather in dust storms and dust devils. For the probe to capture the lightning signal, several conditions had to align: the discharge occurred in a location with a strong and nearly vertical magnetic field, the resulting electromagnetic wave passed through the ionosphere without complete attenuation, the probe was at the correct altitude and position at the time, and the instrument was operating in a mode that allowed for the necessary measurements.

During a discharge, a very short, powerful current is generated, creating fluctuating magnetic and electric fields, and thus an electromagnetic wave propagating in all directions. Part of it penetrates the ionosphere, where the wave slows down and different frequencies travel at different speeds. Consequently, an orbiting probe does not capture the entire signal at once; higher frequencies arrive first because they travel faster. If we converted such a captured signal into sound, we would hear higher tones first, followed by lower ones.

"I went through data from the beginning of the mission, and after automatically filtering records measured outside areas of strong magnetic fields or at excessively high altitudes, I found only a single electromagnetic lightning signal—a so-called whistler—among thousands of possible records," comments František Němec from Charles University on his December 2024 discovery. The entire team then began carefully verifying whether it was indeed a manifestation of an atmospheric discharge. "Based on previous calculations, laboratory experiments, and observations of lightning in the dust plumes of terrestrial volcanoes, we all expected electrical discharges in the Martian atmosphere, but until that moment, no one had recorded them," adds Ondřej Santolík from the Czech Academy of Sciences and Charles University.

The MAVEN probe studied the Martian atmosphere and its interaction with the Sun until communication was lost in 2025. One of its instruments measured electromagnetic waves, but due to data transmission limits, it only measured at selected times and recorded only a thousand values per second.  On June 21, 2015, when the probe captured the lightning signal, no large-scale dust storm was recorded on Mars, but scientists do not rule out a local phenomenon.

To confirm the theory, PhD student Kateřina Rosická performed detailed simulations of the wave passing through the planet's ionosphere. She adapted methods used for Earth to the assumed composition of the Martian ionosphere. The calculations confirmed the observed delay of lower frequencies and the significant attenuation of higher frequencies, consistent with the fact that the probe did not observe the signal at those higher frequencies.

For this whistler to be captured by an orbiting probe, the source lightning had to be significantly stronger than the occasional small discharges measured between 2021 and 2024 by the Perseverance rover directly on the Martian surface. An international team of authors released the first report on their acoustic and electrical manifestations shortly before the Czech researchers published their discovery of lightning detection from Mars' orbit.

The teams from Charles University and the Institute of Atmospheric Physics have long been active in various space projects. Both are involved in designing instruments for the M-MATISSE mission, which, if selected, is scheduled to launch in 2037. "It will be better equipped to search for traces of lightning discharges than its predecessor, MAVEN," notes study co-author Ivana Kolmašová, who also serves as a member of the ESA Scientific Study Team for the M-MATISSE mission.

Infobox: Whistler – This phenomenon was first heard on telephone lines in the early 20th century. It was later revealed to be linked to lightning in the opposite hemisphere. The mechanism and the reason lower frequencies arrive later were described by L. R. O. Storey in 1953.

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