Ramakrishnan, who was director of the Liquid Propulsion Systems Centre (LPSC) here, succeeds P S Veeraraghavan.
A Padma Shri award recipient, Ramakrishnan is an expert in aerospace propulsion, launch vehicle systems and project management.
He had also served as Director (projects) at VSSC and Chairman, Flight Readiness Review and played a key role in accomplishing the PSLV-C11-Chandrayan Mission, a press release here said.
The new director was one of the scientists who took part in the mission to realise India's first satellite launch vehicle SLV-3. He was the mission director for PSLV C1, C2, C3 and C4 flights.