Small‐scale turbulence detected in Mercury's magnetic field

Abstract

With its closest approach a mere 46 million kilometers from the Sun, the blast of the solar wind was supposed to wash away any chance that Mercury could hold on to a magnetic field—an idea rejected by the observations of the Mariner 10 spacecraft in 1974. Though Mercury was shown to harbor a weak magnetic field (one‐hundredth the strength of Earth's), its structure, behavior, and interactions with the solar wind remained heavily debated, yet untested, until the 14 January 2008 approach of NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) orbiter. Using a continuous scalogram analysis—a novel statistical technique in space research—Uritsky et al. analyzed the high‐resolution magnetic field strength observations taken by MESSENGER as it flew within a few hundred kilometers of the planet's surface. The authors found turbulence in Mercury's magnetosphere, which they attributed to small‐scale interactions between the solar wind plasma and the magnetic field. At large spatial and temporal scales the solar wind can be thought of as a fluid with some magnetic properties—a domain well explained by the theories of magnetohydrodynamics.