ESA astronaut Sophie Adenot released a video capturing the unique clicking sound of the International Space Station's TOCA system [1].

The recording provides a rare auditory glimpse into the daily environment of orbital living. By sharing these sounds, the European Space Agency aims to bridge the gap between complex space operations and public understanding of the station's mechanical reality.

Adenot recorded the audio on day 121 [1] of her mission during orbit 1,873 [1]. The clip is the second part of a sound-hunting series [1] and serves as the ninth episode of her "Sunday morning science" program [1].

In the video, Adenot focused on the TOCA system, which she described as her absolute favorite sound onboard the station [1]. She noted the sound occurs even when the system is switched off, a detail she mentioned to preempt concerns from NASA engineering teams [1].

"Day 121, orbit 1873 — Sunday morning science with Sophie, episode 9: Hunting for sounds, part 2," Adenot said [1].

The series is designed to humanize the experience of long-duration spaceflight. While most public space media focuses on silent vacuums or dramatic launches, these recordings highlight the constant mechanical hum, and rhythmic clicks that define the internal atmosphere of the ISS.

"It’s my absolute favourite sound onboard the Station," Adenot said [1].

This effort to document the sonic environment of the station coincides with ongoing efforts to monitor the structural and mechanical health of the aging facility. Though the clicking sound is presented here as a curiosity, the continuous operation of the station depends on the precise functioning of its various support systems.

“"It’s my absolute favourite sound onboard the Station!"”

The release of these recordings reflects a broader trend in space agency communication to move beyond technical data and toward experiential storytelling. By highlighting the 'favorite' sounds of astronauts, the ESA is fostering an emotional connection between the general public and the technical maintenance of the ISS, while simultaneously documenting the acoustic signature of the station's hardware.