Hello reader, the road map for isro after 12th is as follows,

After you complete your 12th from science section

* Appear for JEE exam and secure good rank

* Complete your B Tech degree in Aeronautical,  Electrical and Communication, or Mechanical Department , and after that Appear for

* ISRO Centralized Recruitment Board (ICRB) Exam

The second ways is, after B Tech go for master degree and then get selected by isro

The third way is complete your BSc and MSc in either

* Physics

* Maths or

* Electronic

And then get selected by isro

The fourth way is after you complete your PhD in astrophysics,  space technology or material science you can get a position in isro as research scientist.

So select which option best suits you.

Regards