Dear Aspirant,
Yes,she can go for aerospace  after her b.tech.
She has to give AE paper in GATE
But Aerospace is related to mechanical subject more
In Gate also, question are mostly related to Mechanical engineering which computer science can't understand.
This is problematic situation
Thankyou
Hope it helps

Hello Spandan!

If she is interested in Aerospace then she can do masters(Mtech or MS) in aerospace engineering to follow her interest.She can do M tech by giving gate exam in aerospace engineering and if she scores good marks then she can do M tech from IIT in aerospace engineering.

Hope it answer your concerns.