Martian ionospheric response during the may 2024 solar superstorm.

Parrott, Jacob; Sánchez-Cano, Beatriz; Svedhem, Håkan; Witasse, Olivier; Meggi, Dikshita; Wilson, Colin; Cardesín-Moinelo, Alejandro; Müller-Wodarg, Ingo · Nat Commun · 2026

basic_science · Level V

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Abstract

Solar energetic events can have considerable effects on planetary ionospheres. However, the erratic nature of these solar energetic events make observations difficult. Here we show a mutual radio occultation observation, which serendipitously occurred just 10 minutes after a large solar flare impacted Mars. This resulted in the largest lower ionospheric layer ever recorded, where it was 278% its typical size. We used in-situ soft x-ray irradiance measurements to show a threefold increase in flux. This infers a different relation of soft X-ray to this layer's density than previously thought, with variations depending on the amount of spectrum 'hardening' leading to the increase of ionisation from secondaries.