Hello,

If you have a strong Passion for space /Aerospace engineering/Avionics , then you can choose IIST

If you don't have a specific interest, then you can go IIT to have many other Options

B.TECH COURSES :

B.Tech in Space Technology

B.Tech in Aerospace engineering

B.Tech in Avionics

To become a Space scientist - You should do Masters degree or doctoral degree in Physics, astronomy or astrophysics

So,

For learning Space science,

You should pursue UG in Aerospace engineering or any Course related to Earth and space and also Avionics, then you should pursue PG ( M.Tech or PhD program) in Astronomy and Astrophysics

Hope it helps

Good luck!