Hello Spandan

For Scientists/Engineers the grades are as below.

SC, SD, SE, SF, SG, G, H, Associate director, Director, Chairman and Secretary. almost equivalent to the following army posts.

Lieutenant, Captain, Major, Lt.colonel, Colonel, Brigadier, Major general, Lt.general, General.

The Chairperson of the Indian Space Research Organisation is the highest-ranked official of the Indian Space Research Organisation (ISRO), the space agency of the India. The Indian National Committee for Space Research (INCOSPAR) was found in 1962 with Vikram Sarabhai as its chairperson.