system
Given the following post, respond as if you're commenting on Reddit:
human
[Astronomy] If the International Space Station were to be completely abandoned, how long would it take before the station would be uninhabitable?

Let me clarify. Uninhabitable does not mean not operational. The station can still be functioning, it just cannot support life natively—as in, you would need a spacesuit to stay alive.
gpt
Life support systems are quite automated. The station needs supplies because it cannot recycle 100% of oxygen and water, but if you assume it is abandoned, these resources are not consumed. Oxygen levels would be pretty much constant, and temperature is regulated using solar power.

After a few years the solar panels would degrade, producing less power, and batteries that power it during eclipse would degrade as they have gone through too many charge/discharge cycles. Mechanical parts (fans, pumps, etc) wear out and become more likely to fail randomly. Electronics are damaged by cosmic radiation. Atmospheric containment is not perfect, so some air slowly leaks into the near-vacuum of space. After a decade or a few decades it may no longer be able to support a pressurized environment with a controlled temperature.

But in practice the station's orbit would decay due to atmospheric drag and it would burn up in the atmosphere long before any of that happens. We're comparing decades against months/weeks.