Sorry to say you but you are not eligible for Joining NASA as Astronaut for that you will have to complete your PHD.

Candidates must have PHD degree in one of the following department:

PhD (Astrophysics)
PhD (Geophysics)
PhD (Metaphysics)

Candidates can appear for the entrance exam which is held by the NASA for the recruitment of Scientists, Astronauts etc.

Eligibility:
Citizenship:
Candidates who are joining the ISRO need to be Indian citizens

Age limit:
Candidate should be at least 21 years at the time of joining. The age limit is relax able for candidates belonging to the SC/ST category

Qualification:
Candidates need to be Graduates from a recognized board or University.

Institutes for doing PHD:
Indian Institute of Aeronautical Engineering, Dehradun ( Uttarakhand )
Behind the Upcoming Terminal of Jolly-Grant International Airport , Dehradun ( Dehradun Dist. )- 248140

Bharat Institute of Engineering and Technology (B.I.E.T.), Hyderabad( Andhra Pradesh )
Manglapally,Ibrahimpatnam,Ranga Reddy , Hyderabad ( Hyderabad Dist. ) - 501510

Engineer's Training Centre ( E.T.C), Thrissur( Kerala )
Plakkat Lane, Naikkanal , Thrissur ( Thrissur Dist. ) - 680001

Guru Gram Institute of Aeronautical Engineering and Technology, Gurgaon( Haryana )
Laxman Vihar , M.L Complex, Dhanwapur Road, Opp. Sec 4, (NCR Delhi) , Gurgaon ( Gurgaon Dist. ) - 122001

Guru Gram Institute of Aeronautical Engineering and Technology, Nagpur( Maharashtra )
Royal Complex - 467 , Near Old Paradi Naka, Bhandara Road , Nagpur ( Nagpur Dist. ) - 440008

Guru Nanak Engineering College, Hyderabad( Andhra Pradesh )
Ibrahimpatnam, RR District. , Hyderabad ( Hyderabad Dist. ) - 501506