Dear Aspirant,

To be an Astronaut you need to be Fighter Pilot in Indian Airforce, ISRO select only Airforce Officers to assign them or send them on a mission as a Astronaut. To be an officer in Indian Airforce you need Physics and Maths as a compulsory subject in 12th, after that you can either join NDA or after b.tech, give CDS/AFCAT exam to complete your training from Airforce Academy. As you don't have Math's or not any above then this option is useless for you, talking to the second one

To be an Astrobiologist you just need a science degree with good marks and after that complete your PHD from the selective course, that's it. After completing your Master's degree you can apply for the post.

Best Of Luck!!!