The scenic tour of the Venusian subsolar magnetosheath by BepiColombo

As Venus lacks an intrinsic magnetic field, such as Earth’s, and crustal magnetic fields, such as Mars’, its conductive ionosphere interacts directly with the solar wind, and an induced magnetosphere is created. Therefore, the Venusian magnetosheath is one of the few examples of a gas-dynamics dominated interaction region in the solar system. Measurements of this region can help us investigate the energy transfer from the solar wind to the ionosphere of non-magnetised bodies and properties of stagnated flow near the subsolar point, without complications from magnetic fields of planetary origin.

Even though several missions have visited Venus, none of them have been able to provide high time resolution plasma particle measurements of the subsolar magnetosheath. With the 2^nd Venus flyby by BepiColombo on August 10^th 2021, we had the rare opportunity to make a complete tour of the Venusian magnetosheath, using measurements from several plasma instruments onboard, as the flyby passed from the nightside flank towards the stagnation region near the subsolar point and out through a quasi-perpendicular bow shock. The observations were made during the extremely rare opportunity when the Solar Orbiter spacecraft was located upstream and could provide complementary solar wind observations, which showed very stable solar wind conditions during the scenic tour. This meant that we had the chance to, for the first time, probe the full spatial structure of the Venusian magnetosheath, without large temporal variation induced by solar wind fluctuations.