Hi Vivek,
First of all congratulations for following this endeavour! Hee are some of the guidelines you can use:
1. Clearing the ‘Joint Entrance Exam’ help by the IITs through which one can join ISRO
2. Clearing the entrance exam held by NASA for the recruitment of scientists and astronauts
Check this link for for more info and list of collges:
https://www.shiksha.com/aviation/articles/career-as-an-astronaut-blogId-809
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