Arunachalam was the founder-chairman of Center for Study of Science, Technology and Policy, a not-for-profit think-tank, in Bengaluru. He is survived by his wife, three children and six grandchildren.
His career spanned across Bhabha Atomic Research Centre (BARC), National Aerospace Laboratory (NAL), and Defence Metallurgical Research Laboratory. He served as the scientific adviser to the defence minister from 1982 to 1992. He worked as secretary, department of defence research and development, and was also the director-general of DRDO.
“He was conferred the Shanti Swarup Bhatnagar Award, Padma Bhushan, and Padma Vibhushan for his contributions to engineering, science and technology. He was a Fellow of the Indian National Science Academy, the Indian Academy of Sciences and the Indian National Academy of Engineering.