On the arrival of the Space Weather event of May 2024 at Mars and its impact on the Martian Ionosphere

Abstract

During May 2024, Mars experienced a space weather event driven by solar active region AR13664, the same region that produced the superstorm of 10 May 2024 at Earth. We investigate the arrival and impact of the interplanetary coronal mass ejection (ICME) on 17 May 2024 at Mars using heliospheric simulations, energetic particle observations, and ionospheric measurements. The CMEs observed on 14 May 2024 were used as inputs to the Solar Transient ARrival (STAR), Drag Based Model (DBM), and WSA-ENLIL models. All the simulations confirm the CME arrival at Mars on 17 May 2024, with WSA-ENLIL predicting an earlier arrival by ~12 hours compared to the STAR model. The simulated solar wind velocities and densities are consistent with in situ observations by MAVEN. The Solar Energetic Particle (SEP) flux enhancements on 16–17 May further confirm the CME arrival, with a shock-related increase preceding the main ejecta. The ion density profiles ($O_2^+$ and O+) derived using the Neutral Gas and Ion Mass Spectrometer (NGIMS) reveal significant ionospheric changes, including a lower ionopause and the depletion of $O_2^+$ during the event compared to the solar quiet time. These results provide multiple lines of evidence for the CME arrival at Mars, validating the STAR, DBM, and WSA-ENLIL models for solar transient propagation at ~1.5 AU and also highlighting its strong impact on the Martian plasma environment.