Role of ULF Waves in Reforming the Martian Bow Shock

Abstract

Understanding the nature of planetary bow shocks is beneficial for advancing our knowledge of solar wind interactions with planets and fundamental plasma physics processes. Here, we utilize data from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to investigate the Martian bow shock, revealing its distinctive characteristics within our solar system. We find that unlike other planetary shocks, the reformation of Mars's bow shock driven by the ultra-low frequency (ULF) waves is more global and less dependent on shock geometries. This distinct behavior is attributed to the broad distribution of ULF waves in the upstream region at Mars, generated not only by shock-reflected ions but also by planetary protons. Additionally, during the reformation process, the amplitude of the ULF waves and the steepened structures are significantly large. This results in the newly reformed shock exceeding the original one, a phenomenon not observed at other planets under similar shock conditions. Therefore, the ULF waves significantly enhance the complexity of shock dynamics and play a more substantial role at Mars compared to other planets.