University of Iowa physicists have identified a possible driving force behind massive disturbances in the magnetic environment of Mars. 

In a new study, the researchers analyzed the constituents of Mars’ magnetotail — magnetic plume that extends outward from the planet for more than 1,500 miles. The magnetotail forms when a powerful jet of energy from the sun, called the solar wind, stretches the far side of the red planet’s upper atmosphere. 

Scientists collected data from November 2021 to February 2024 from two spacecraft — NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) and Tianwen-1 (TW-1). The spacecraft flew at the same time through two separate regions of Mars’ magnetotail. MAVEN traveled upstream, in the direction of the incoming solar wind, while TW-1 observed downstream, where the solar wind flows past and away from Mars.

Yuanzheng Wen, a graduate student at Iowa and the study’s corresponding author, says scientists believe that on Earth, a process called magnetic reconnection, where the solar wind collides with our planet’s magnetic shield, may trigger electric currents within the magnetotail, motions known as “flapping.” 

He and Jasper Halekas, professor in the Department of Physics and Astronomy, wanted to find out whether magnetic reconnection spawned the flapping observed in Mars’ magnetotail — and perhaps occurred with other planets in the solar system — or whether that process was unique to Earth. 

Data from MAVEN and TW-1 enabled the physicists to determine that approximately two-thirds of flapping events observed by TW-1 coincided with magnetic reconnection signatures logged by MAVEN. 

“We're just in the infancy of what we know, since this is one of the first times that we've been able to do a two-point study of this process,” Halekas says. “But it already tells us that this process can happen not just on Earth but in such a different environment as Mars.”

Wen emphasized that the study shows magnetic reconnection on Mars is a possible — but not definitive — trigger for magnetotail flapping. 

That’s in part because one-third of the flapping events did not coincide with magnetic reconnection. That points to other possible factors, such as the tail being created solely by the solar wind. While solar wind creates the magnetotail, the one-third of uncorrelated flapping events points to it also playing a part in directly causing flapping.  

Wen said pinpointing the solar wind’s direct influence on Mars may be more difficult because Mars’ atmosphere is different from Earth’s. 

Earth has a global magnetic field that deflects most charged particles from the solar wind away from the planet. Mars has no global magnetic field; instead, its magnetic field is created by its interaction with the solar wind, leaving that field’s direction, shape, and strength highly sensitive to changes in the solar wind. 

Small shifts in magnetic field direction can alter the structure of the tail and create signatures resembling magnetic flapping. Because both MAVEN and TW-1 were positioned within the tail region during the observations, no spacecraft was available to directly measure the solar wind and determine whether changes there created the flapping events. 

The ESCAPADE and MMX missions will allow researchers to make more detailed analyses. ESCAPADE launched in November 2025; MMX will launch later this year. 

“I think we're in a very good time right now because in the past, people had no platform like this with multiple spacecraft to study this. Now, we have several platforms to do so,” Wen says. “I feel fortunate that we have these assets there at Mars to do that.”

The study, “Magnetic Reconnection as a Potential Trigger for Magnetotail Flapping at Mars: Insights From MAVEN and Tianwen‐1 Observations,” was published online April 13 in the journal AGU Advances.

Han-Wen Shen, a postdoctoral research scholar in the Department of Physics and Astronomy at Iowa, is a study co-author. Other authors include Chi Zhang, Jiawei Gao, and Chuanfei Dong, from Boston University; Robert J. Lillis, Yingjuan Ma, Junfeng Qin, Shaosui Xu, David L. Mitchell, and James P. McFadden, from the University of California; Norberto Romanelli, from the University of Maryland; Long Cheng, from the Swedish Institute of Space Physics; Yaxue Dong, David A. Brain, and Shannon M. Curry, from the Laboratory for Atmospheric and Space Physics; Jared R. Espley, from the NASA Goddard Space Flight Center; and Christian Mazelle, from the Université de Toulouse, in France.

The study was funded by NASA through the MAVEN mission. Researchers used publicly available data from TW-1 and had no direct collaboration with China.