ISRO Scientists study subjects Maths and Physics at 10+2 level and they have basic knowledge about the subject. In graduation you should try to crack NITs and IITs  to take admission in engineering program and you can take degree in B.Tech in Aerospace Engineering, Mechanical Engineering, Radio Engineering, and Engineering Physics.To get selected in ISRO make sure you get good grades in your academics.

After completing B.Tech from any college, an examination namely ICRB (centralized Recruitment Bangalore) is conducted by ISRO and individuals are tested as per their respective branches of engineering and after clearing the interview, one can get appointed as a scientist or an engineer at ISRO. Candidates must have a minimum aggregate percentage of 65% and above in B.tech in their respective relevant streams.

After the completion of M.Tech or D. in trades such as Geoinformatics, Remote Sensing, Instrumentation, applied Mathematics, Geophysics, Geography or any other equivalent degree in the field of Physics or Mathematics one can apply directly for the job of a scientist at ISRO. The selection consists of written exam and Interview and after clearing these sages scientist/Engineer position can be obtained in ISRO.

All the Best!!