system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How did engineers know how to design a suit that would protect astronauts on the moon?

Did they just design them to protect from everything they could think of or were they somehow able to determine exactly what the suits would be up against?
gpt
The suit was based on a deep sea diving suit and air craft suit combined.  Then it was modified for temperature and all sorts of things.  They still use the deep tanks for acclamating astronauts to their suits.  

The whole design aspect is worth reading and learning more about.