They all require citizenship ... all of them including NASA, JPL, NSA, and even a police officer. I had a passion for all at one point or another and seeing "must be US Citizen" is the biggest disappointment.
Recently I got into cyber security related topics and then realized that you can't get anywhere with that either since every company requires a clearance which requires you to be a citizen and rarely, a permanent resident.
Well, back to reality and finding new interesting subjects.
Good luck hombre