Solar Superstorm Expands Mars's Ionosphere, Revealing Space Weather on the Red Planet
A May 2024 solar superstorm from sunspot AR3664 produced an X2.9 flare and a coronal mass ejection that not only triggered a major Earth geomagnetic storm but also dramatically swelled Mars’s lower ionosphere—nearly threefold—as solar plasma and X‑rays flooded the planet’s upper atmosphere. ESA’s Mars Express and the ExoMars Trace Gas Orbiter used radio occultation to measure the changes, showing how solar activity injects energy and particles into Mars’s atmosphere and highlighting its ongoing atmospheric loss. The orbiters briefly glitching during the storm but ultimately recovering demonstrates the value of radiation‑hard spacecraft for space weather studies.
