The magnetometer (MPO-MAG ) on board of the Mercury Planetary Orbiter, one of the two orbiters comprising the BepiColombo mission, made measurements of Earth’s magnetic field during the spacecraft’s flyby of Earth in April 2020.

The audio, accompanied by the animation, is a sonification of the captured data created by the MPO-MAG team and not an actual sound recorded in space. The audio, compressing 8 hours of recorded data into a 26-second audio track, shows the moment when BepiColombo encounters the so-called bow shock at the outer edge of the Earth’s magnetosphere where the Earth’s magnetic field interacts with the solar wind. The spacecraft then passes through the magnetosheath, a turbulent region still considerably affected by the cosmic plasma, and crosses the magnetopause, the boundary after which the magnetic field of Earth dominates.

After that point, the sound of BepiColombo’s reaction wheels, which keep the spacecraft oriented in the correct direction, comes to the fore in the recording.

According to MPO-MAG Principal Investigator Daniel Heyner, of the Technical University of Braunschweig, Germany, the team could use the data recorded during the flyby to calibrate the instrument and prepare it for future measurements. The magnetometer will be on for most of BepiColombo’s seven-year cruise to the innermost planet of the Solar System, measuring the solar wind at various distances from the Sun.

The Earth flyby on 10 April 2020 was one of the overall nine gravity-assist manoeuvres required for BepiColombo to adjust its trajectory and close in on Mercury. During the manoeuvre, BepiColombo got as a close as 12 689 km to the surface of Earth and captured a series of stunning images of the planet.