Hi dear

Yes, you can do M.tech with any branch or specialization. But you need to clear the GATE exam.

The GATE exam stands for Graduate Aptitude Test For Engineering. Its eligibility is :-

* Bachelor's degree in field of Architecture, Technology or Engineering.

* Msc in any branch of Science, Mathematics, Computer Science or Statistics..

So, you are eligible for this exam. Just go through the official website of GATE 2020 once and apply for the exam.

After clearing the exam, you can do mtech from  aerospace engineering.

All the best :)