Photo credit: www.esa.int

ESA/JAXA’s BepiColombo Spacecraft Completes Final Mercury Flyby

On January 8, 2025, the ESA/JAXA BepiColombo spacecraft successfully executed its sixth and final flyby of Mercury, utilizing the planet’s gravitational pull to aid in its trajectory toward entering orbit around Mercury in 2026.

The accompanying audio track from this event features real vibrations recorded by the Italian Spring Accelerometer (ISA) instrument on board the spacecraft. To render these vibrations audible, the frequency of the data has been adjusted, transforming one hour’s worth of measurements into a one-minute sound experience.

The BepiColombo spacecraft is in a constant state of slight movement. This subtle motion is attributed to various factors, such as the movement of fuel within its tanks, the natural vibrational frequency of the solar panels, and the circulation of vapor through the heat pipes. Collectively, these occurrences produce a haunting undercurrent of sound throughout the video.

As BepiColombo approaches Mercury, the ISA instrument captures additional forces impacting the spacecraft. Notably, the most intriguing sounds resemble short, soft bongs. These are generated when the spacecraft transitions into and out of Mercury’s shadow, where it momentarily loses exposure to sunlight. A core objective of the ISA is to monitor fluctuations in solar radiation pressure, which is the force exerted by sunlight on the spacecraft while it orbits the Sun and heads towards Mercury.

The most pronounced noises, described as a deep ‘rumbling,’ result from the rotation of the spacecraft’s expansive solar panels. The video captures the initial rotation during the shadow phase at the 00:17 mark, with a second adjustment noted at 00:51, documented by one of the spacecraft’s monitoring cameras.

Faint sounds reminiscent of wind captured in a phone call become more discernible approximately 30 seconds into the video. These sounds occur due to the varying gravitational effects Mercury exerts on different sections of the spacecraft, resulting in slight stretching. This structural response is accompanied by adjustments made by the onboard reaction wheels, which shift their speeds to maintain the spacecraft’s orientation, a change reflected in the audio as a frequency variation.

This flyby marks the last significant opportunity to measure many of these effects with BepiColombo’s large solar panels, which heighten the spacecraft’s susceptibility to vibrations. The module housing these panels will not remain in orbit around Mercury alongside the mission’s orbital craft.

The video presentation includes a precise simulation of the spacecraft’s trajectory during the flyby, created using the SPICE-enhanced Cosmographia spacecraft visualisation tool. Additionally, around the 38-second mark, viewers are treated to actual images taken by one of BepiColombo’s monitoring cameras.

For further details, read more about BepiColombo’s sixth flyby of Mercury.

You can also access related broadcast-quality video materials.

Source
www.esa.int