Every year ICRB or ISRO central Recruitment Board releases advertisements for different vacancies. Now this have a lot of deviations in qualification according to the requirement of job. For example, there are advertisements for Drivers which needs a 10+2 pass, for technician a Diploma is required, for Management and Administration MBA is required, For Scientist MSc/BTECH/MTECH/BARCH/MARCH required, for stenography , a certificate in Stenography is required. So there are a lot of respective posts in ISRO. So based on your aspirations the education qualification will depend.

For the ISRO career section copy paste the link below on your browser:

https://www.isro.gov.in/careers

I hope this answer helps. All the very best for your future endeavors!