Hey Akash

There are strict height requirements for aspiring astronauts.

To be a commander or pilot astronaut, you need to be 158 to 190cm tall,NASA says.To be a mission specialist, however, there a little more leeway – “between 58.5 and 76 inches” which is 149 to 193cm.

A commander is responsible for  the mission’s success, the safety of the crew and shuttle itself. The pilot astronaut assists the commander - they have a more technical role in operating and controlling the shuttle.

A mission specialist assists both the commander and pilot by coordinating the running of the shuttle which includes “crew activity planning, consumables usage, and experiment/payload operations.”