See you can do BTech in Aerospace Engineering, but if you go for the BTech in Mechanical Engineering, then the fields where you can work after your BTech widens up. As Aerospace Engineering is a sub branch of Mechanical Engineering, studying ME will give you a broader understanding regarding the dynamical systems & system design. If you go for the Aerospace Engineering in your BTech then you will have to study sudden subject of ME itself, so academically there is not much of demerit if you are certain that you want to go for Aerospace industry only. But if you have any kind of doubt or if you want some broader perspective in Jobs, then I would suggest you to have a ME followed by MTech in AE.

For more information regarding ME you can consider the link below:

https://www.careers360.com/courses/mechanical-engineering-course

For more information regarding AE you can consider the link below:

https://www.careers360.com/courses/aerospace-engineering-course

I hope this helps. Goodnight!

It might not be possible for you to study master of technology in aerospace engineering after completing Bachelor of Technology in mechanical engineering. This is because the minimum basic eligibility criteria of most of the colleges and Universities states that the candidate must have completed his bachelors Degree  in aerospace engineering. The other eligibility details for master Technology aerospace engineering are as follows:

1. The candidate needs to complete bachelor of technology in aerospace engineering with at least 50% marks in the aggregate.
2. There are some universities and colleges which accept the valid score of GATE for giving admission in master of technology aerospace engineering.

Read more about Aerospace Engineering Colleges:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/colleges/list-of-me-mtech-in-aerospace-engineering-colleges-in-india&ved=2ahUKEwj3tfPc5aL2AhUVBd4KHStODscQFnoECA0QAQ&usg=AOvVaw2l9K99U5QltDPlT3fQSIbT