Not all astronauts are engineers. While Kalpana Chawla did do her engineering from Punjab University and went on to do her masters in the US, Rakesh Sharma was an Indian Airforce Pilot. Ravish Malhotra did not get to go in space but trained for it as a stand by for Rakesh Sharma. He also was an Airforce pilot. Either way getting to be an astronaut is rare in India even if you do aeronautical engineering or B.Sc. I suggest you check the NASA website and how an astronaut is chosen. Do some research and then you can figure it better. All the best!