Hello student,

you can but you will find it difficult because of non-related stream 

Hello Mukesh,
Eligiblity criteria for admission to the M.Tech Aerospace Engineering programmes is the candidate should have B.E. or B.Tech degrees in Aerospace / Chemical / Civil / Electrical / Electronics / Mechanical Engineering or Computer Science.So, Yes, your friend can do M.Tech in aerospace engineering.

For admission he has to qualify in Graduate Aptitude Test in Engineering (GATE). GATE is conducted once every year in the month of Feburary. The forms for the same are filled in October month of the previous year.
For eg. To appear in GATE in feburary 2020 form should  be filled in October 2019.
After qualifying GATE, he can apply to institutes which offer the M.Tech. Aerospace Engineering Program. Few institutes offering the course are:

• IIT, Kharagpur
• IIT, Chennai
• IIT, Kanpur
• IISc Bengalore
• Jain University, Bengalore
• Parul University, Vadodara 
• Manipal Institute of Technology, Karnataka
• Amity University, Noida

Hope I answered your query,feel free to ask further questions.