No! You are not eligible for ISRO Exam. The eligibility criteria for ISRO is as follows

A candidate must have completed their B.E/B.Tech with at least 65% from recognized Universities are eligible for Indian Space Research Organisation exam...

Age should be between 21-35 years for General category. There is a Relaxation is available for OBC +3 years and for SC/ST +5 years on Upper age...

A candidate have Nationality of India.

But medical student after completion of graduation can join isro as an Authorized medical officer. Apply as and when vacancies are there. But vacancies are very few in no. so you should try hard.