Direct Evidence for Cross-scale Energy Transfer in Mars’s Space

Like Earth’s space, the Martian space constitutes a collisionless plasma environment. Consequently, the cross-scale energy transfer inherent to the multi-scale nature of collisionless plasmas—a process widespread in Earth’s space—is theoretically expected in Martian space. However, direct evidence for cross-scale energy transfer driven by cross-scale wave-particle interaction—the new model established in Earth’s space—remains elusive in Martian space. Utilizing data from the Mars Atmosphere and Volatile Evolution (MAVEN) and Tianwen-1 spacecrafts, we present the definitive observational evidence for the existence of such process in Martian foreshock region. Fast magnetosonic waves drive enhancements of electron perpendicular energy at their crests through Betatron acceleration, producing a perpendicular temperature anisotropy of the 20–200 eV population to supply the free energy for the excitations of whistler-mode waves. This process constitutes a direct manifestation of energy cascade from ion down to electron scales. Our study discovers a shared process in the terrestrial and Martian space, a finding that can carry broad implications for understanding space environments across planetary systems.