Hello Aspirant,
As per your question I would say that you need too crack the GATE entrance exam after M.Sc to study M.tech. But it is not possible to do MS in aerospace engineering. 12th Science stream (Physics, Chemistry and Maths) is needed. At post-graduate level aerospace engineering is most of the degree courses.
Hope the information is helpful
All the best

Dear student,

To be precise , a lot of students pursue MTech in other branches after MSc in physics, hence you may do the same as well by getting a good score in GATE, however you need to keep in mind that a few universities might not allow you to pursue MTech in other branches, so choose the university carefully after being thorough with its eligibility.    Take a correct decision after looking at every aspect, visit the college or university, mail them, or contact on helpline number and then take a prudent decision.