It appears that there has been a tiny air leak in the International Space Station for months that they have been unable to identify, and they finally found it using loose tea leaves:
The International Space Station has been leaking an unusual amount of air since September 2019.
At first crew members held off on troubleshooting the issue, since the leak wasn’t major. But in August the leak rate increased, prompting astronauts and cosmonauts aboard the orbiting laboratory to try to locate its source in earnest.
Roscosmos, Russia’s space agency, announced on Thursday that crew members had finally pinpointed the leak after devising an unusual test: They let tea leaves guide their search.
The cosmonaut Anatoly Ivanishin released a few leaves from a tea bag in the transfer chamber of the Zvezda Service Module, the section of the station’s Russian segment that houses a kitchen, sleeping quarters, and bathroom. Then the crew members sealed the chamber by closing its hatches and monitored the tea leaves on cameras as they floated in microgravity.
The leaves slowly floated toward a scratch in the wall near the module’s communication equipment — evidence that it was a crack through which air was escaping.
Behold the power of tea.