hii

it should be all upon you what topic you wanna go for but as my personal opinion i'll suggest you to go for satellite one as there would be  all which is currently experienced and all currently under research and also this is much more exciting and the easier one .next you may go for astrophysics and followed by space robotics  rocket propulsion and than mars but if you wanna something more new discoveries  and purely new than just reverse my order..

thanks