Hey!

The minimum requirement for an astronaut is bachelor's degree in any of the courses for example engineering, biological science, physical science, or mathematics etc. You have to work super hard for becoming astronaut at NASA as the competition is the toughest.And to be selected as an astronaut there are several physical parameters,one has to qualify ,which are essentially required so you have to focus on those aspects as well.

For becoming an astronaut you can pursue any bachelor's degree but as you are from MPC stream you can go for B.tech in the related field or  B.Sc. honors/major in Physics with Mathematics as a secondary subject  and in future you will be able to choose the major field like Astrophysics,Astronomy etc.

Hope this helps