Hii Naveen!
It's nice to see you interested in becoming a scientist. We need more scientists in our country:) In order to become a scientist and that to specifically at ISRO there are certain eligibility criteria. Every year recruitments are done accordingly. You will get detailed information on the same in the link provided below -
https://www.google.com/amp/s/engineering.careers360.com/articles/isro-recruitment/amp
Hope this helps.
All the best!