Greetings Dear Aspirant,

As you've already mentioned that you have PCM as your main subject in your class 12th and this is pretty good for being an astronaut.

So, To become an astronaut, what you need to do is to maintain a strong grip on Physics, Chemistry and Mathematics as these fields are very complex, pass your class 12th from a recognised board.

After your schooling is done, you should pursue a bachelors degree specifically in Engineering as you will have more chances in future. Then you need to hold a master's degree as more preferences are given to those students who have PhD and Master's degrees.

Colleges for Astrophysics courses:

• Indian Space and Research Organisation, Bangalore
• Punjabi University, Punjab
• IIT Bombay, Mumbai
• Indian Institute of Science, Bangalore
• IIT Madras,Chennai
• IIT Delhi,New Delhi
• Tata Institute of Fundamental Research (TIFR), Mumbai
• Delhi University
• IIT Kharagpur
• IIT Madras

Hope you get your answer.

Also, check out this link for detailed information:

https://www.careers360.com/careers/astronaut

Thank you and good luck:)