As you want to get the details of process to join NASA as an astronaut so here is the information of the same for you:

In order to join NASA you should be a American national and you should possess a minimum qualification of PhD in Astronomy.

Getting into NASA is a dream of many and its not an easy task.

If you do some good research work in Astronomy and able to bring out new things out then you would have a good chance to join NASA.

In order to turn your dream a reality its better you should possess a Masters and Doctorate degree from US top universities.