NASA's MAVEN Detects 30%-40% Plasma Depletion at Mars After 2023 ICME Impact
Updated
Updated · Nature.com · May 18
NASA's MAVEN Detects 30%-40% Plasma Depletion at Mars After 2023 ICME Impact
1 articles · Updated · Nature.com · May 18
Five magnetic structures seen by MAVEN near a 185-km periapsis on Dec. 10, 2023 squeezed Martian ionospheric plasma tailward, cutting local density by 30%-40% at their leading edges.
A coronal mass ejection shock had hit Mars 12-13 hours earlier, leaving a compressed, disturbed magnetosphere in which roughly 50 nT magnetic pulses amplified the normally hard-to-detect Zwan-Wolf effect.
The observations show the effect can operate inside the ionosphere of an unmagnetized planet, with plasma depletions approaching half the original density and flow deflections of about 23° along draped magnetic fields.
Researchers say the process likely runs continuously at Mars but usually stays below instrument detection thresholds; during quiet conditions, the expected deflection would be only about 0.6°.
The finding broadens evidence that space weather can reshape atmospheres at unmagnetized bodies such as Venus, comets and Titan, though MAVEN could not measure how the energy dissipated below its altitude.
Does this 'plasma-squeezing' effect mean Mars loses its atmosphere even faster than we previously believed?
Could this powerful solar wind interaction pose an unexpected radiation threat to future human colonists on Mars?
With the MAVEN spacecraft now lost, how will NASA's rovers on Mars phone home to Earth?
Extreme Space Weather at Mars: MAVEN’s December 2023 ICME Findings and Implications for Atmospheric Evolution and Exploration
Overview
In December 2023, Mars was struck by a powerful interplanetary coronal mass ejection (ICME), giving the MAVEN mission a rare chance to observe how an unprotected planet responds to extreme solar activity. Without a strong global magnetic field, Mars’ atmosphere is directly exposed to solar radiation and energetic particles. MAVEN recorded dramatic disturbances in the Martian magnetosphere and ionosphere, including large magnetic structures and intense pressure gradients that squeezed plasma tailward. These changes led to significant plasma depletion and revealed how space weather events can rapidly alter Mars’ atmosphere, highlighting the planet’s vulnerability and the importance of understanding these processes for future exploration.