I’m working on an indie game that deals with Space Sciences. I’m nearby a well-known university for aerospace and space sciences and could use some guidance from people that know the subject well. The university’s faculty directory helped me find potential contacts but I’m not too sure on the proper etiquette for contacting them.

Do I just contact a few of them individually to their uni emails? Do I contact their provided phone numbers? Do I reach out to the Department Head and ask for their guidance? Is payment usually expected for an initial conversation like this?