Hi,

You could appear for GATE and apply for M.Tech at IIST which is connected to ISRO. However that is no guarantee that you will be placed in ISRO. Mostly the recruitment is for post graduates in engineering when I look at the ISRO recruitment careers section. I would advise you to do the same. So you know which course you are best suitable to take up if you were to pursue your PG further.

You can be recruited as a scientist and not through a course. ISRO as such doesnt offer any.