Day 121, orbit 1873 — Sunday morning science with Sophie, episode 9: Hunting for sounds, part 2.

Before anyone from the NASA engineering teams starts wondering why the TOCA is clicking while it’s switched off… I obviously could not turn it on just for the purpose of this video, so I recorded the sound later on during actual operations. It’s my absolute favourite sound onboard the Station! The sound consists of the checkout of several valves, which are used by this Total Organic Carbon Analyzer. This beautiful piece of engineering is used to test the quality of the Station's drinking water. 98% of the water onboard is recycled, isn’t it amazing?