Induced magnetosphere of Mars responds fast to interplanetary magnetic field rotation

Interactions between the ionospheres of unmagnetized bodies and ambient plasma flows form induced magnetospheres. The induced magnetosphere is generally affected by external magnetic fields. Observations of response processes of the induced magnetosphere to external magnetic fields are important for understanding global dynamical processes in unmagnetized planets. Here, using simultaneous observations of Tianwen-1 and Mars Atmosphere and Volatile EvolutioN missions, we show the response of Mars’ induced magnetosphere to interplanetary magnetic field (IMF) rotation. The magnetic field in Mars’ induced magnetosphere rotated within at least 165 seconds following the sudden IMF clock-angle change and gradually stabilized. The convective electric field rotated accordingly, bringing the pickup oxygen-ion plume into the spacecraft’s field of view within 3 minutes. These short timescales demonstrate that Mars’ induced magnetosphere is highly dynamic and sensitive to external magnetic-field variations. IMF changes should therefore be regarded as a common form of Mars’ space weather, highlighting the importance of upstream IMF monitoring and short-term forecasting.