Venus Magnetic Fields from Satellite Data

Abstract

Venus exhibits a distinctive magnetic environment among the terrestrial planets. It lacks a global intrinsic magnetic field, and no global signatures of crustal remanent magnetization have been observed. Instead, Venus displays an induced magnetosphere, formed by interactions between the solar wind and the interplanetary magnetic field (IMF) with the planet’s upper atmosphere. Using satellite data from the Pioneer Venus Orbiter and Venus Express missions, we characterize large scale structure and variability of Venus’s magnetic environment. Our analysis reveals that magnetic field variations are strongly influenced by three main factors: local solar time, with marked differences between the day and night sides; latitude, with equatorial regions exhibiting stronger fields and sharper boundaries than polar regions; and the solar cycle, with larger field amplitudes and lower variability during periods of low solar activity, and weaker but more variable fields during high solar activity. We further investigate the potential presence of crustal remanent magnetization in the Maxwell Montes region by analyzing low-altitude orbits. No clear altitude dependent decrease of the magnetic field and no spatial coherence among orbits is observed. However, the limited spatial and altitudinal orbital coverage prevents a conclusive assessment of signals. To evaluate the detectability of internally generated signals, we create a magnetization model of the region and simulate magnetic field signatures under varying crustal heat flux and magnetization scenarios. Our forward modeling results indicate that only large-scale topographic features can be resolved from orbital altitudes. The computed magnetic amplitudes are comparable to the external background field and fall below its typical fluctuation range, rendering internally generated fields hard to detect. While crustal remanence remains unconfirmed, we highlight the need for future low altitude magnetic surveys to better constrain Venus’s internal structure and magnetic history.