Hello Saichandu. Thanks for contacting Careers360 and we hope we will be able to answer your query. 

Please follow these steps carefully:

1. Do MS (preferably from USA) - you can change stream if you want, to something more relevant to space operations. 

2. Do PhD (definitely from USA) - your change of field in MS will come to use here. 

3. Do Post doctoral research in your interest field, keeping in mind what NASA may need in future

4. Stay in a college as a professor and do research related to NASA. One fine day they might call you for further assistance OR Do things related to your interest field (also related to NASA's projects) in some research lab. E.g. Be a particle physics researcher, be an electronic engineer for flight systems etc.

Needless to say you MUST keep yourself updated with the projects going on in NASA and improve your resume accordingly. 

There is no quick way to get into NASA. 
Also, keep your options open for SpaceX, ISRO etc. You need to definitely work hard.

Also, please see this Quora question fro more information:

• https://www.quora.com/How-do-I-get-a-job-at-NASA-2?encoded_access_token=5f1d9e19bab4439598bb0a4897f3765e

Hope this helps you and all the best!