system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what astronauts are actually doing for months on the International Space Station besides maintaining the facility?
gpt
There are thousands of experiments that scientists down on Earth want done, but in microgravity. These scientists submit their proposed experiments to be brought up to the ISS, and some are selected to be done. Then, the astronauts are trained to complete the experiments and to be able to accurately document the findings. 

These experiments basically cover the entire range of the natural sciences. From hydroponics in microgravity to the long term effects on the human body, to getting details about geologic features that you can't get on the surface. They are pretty much the only people who have professional-level training in *all* disciplines of science.