Do you need a high IQ to work for all the important jobs at space agencies?
A high IQ helps, but keep in mind that some people with high IQs don’t do much with their lives. A high IQ will help you understand academic things better, but it doesn’t give you your drive and work ethic. You don’t need a high IQ, but it helps. You do however need to be knowledgeable on astronomy and you need a degree. I’d look into what kind of degrees they want and the types of jobs they offer. Just be competent and know your stuff.
