Dr. Raj Kumar Choudhary leads the RSIM section at SPL, VSSC, where he pioneered the use of radio science for probing lunar and planetary ionospheres. He is Principal Investigator (PI) of the RAMBHA-DFRS experiment on Chandrayaan-2 and the proposed RAVI payload for ISRO’s Venus Orbiter Mission. As ISRO’s lead scientist under the ISRO–JAXA Akatsuki collaboration, he contributed to the discovery of a new plasma layer in the Venus ionosphere.

His work on the lunar ionosphere using Chandrayaan data and MOM's radio signals has advanced understanding of space plasma environments and solar wind interactions. He initiated India's InSWIM program for space weather monitoring and led the development of 3D ionospheric models for the Moon and Venus. He also leads the NAVIC-based PlasDEM experiment for plasmaspheric studies.