Hi Aspirant!

NASA is a US Governmental Agency.

You can check out different opportunities available in NASA. No doubt, first one you think about is astronaut but there are other opportunities as well such researchers, engineers, geologists, microbiologists, physicists , medical doctors, nurses, and mental health care professionals, Computer programmers and IT specialists etc.

But as you asking about what to do after entering into ISRO. So, first you must choose the opportunity for which you have joined ISRO. For example, you have joined ISRO as a researcher. Then you can look out for the opportunity/vacancy available in NASA for same. Then you can apply for that easily by checking out the eligibility criteria for same on the official website of NASA.

Thankyou!