How to join NASA as a Planetary or Astrophysics Scientist?

I am a Physics Graduate from India and would like to work on Advanced Planetary Science exploration, hence I want to know how to or what are the parameters / prerequisites / qualifications to join NASA as an Indian? Will a PhD in Astrophysics or Planetary Science be enough?|||If you just finished your PhD, you could apply for a post-doctorate position. Here's the main site - it doesn't say you have to be a US citizen (on there at least). http://nasa.orau.org/postdoc/application鈥?/a>