CHENNAI: In a surprise move, the government has appointed Shailesh Nayak , secretary in the ministry of earth sciences, as the ad-hoc chairman of Indian Space Research Organisation ( Isro ).

Sources told TOI that the appointment is only for a month, after which he may be asked to continue or a new chairman may be brought in. K Radhakrishnan , who was given an extension earlier this year, retired on Wednesday.

Nayak, 61, a geologist from MS University, Baroda, had a stint in Isro till 2000. He was earlier the director of Indian National Centre for Ocean Information Services (Incois), Hyderabad.

While Radhakrishnan has been on an extended tenure, the names of Satish Dhawan Space Centre director M Y S Prasad and Space Application Centre director Kiran Kumar were making the rounds, but Prime Minister Narendra Modi found merit in neither of them.

As Isro enters a crucial phase of planning manned missions and interplanetary exploration, scientists feel, the organisation needs a strong person at the helm, preferably someone who straddles rocket science and administrative skills.

“This seems to be an ad hoc measure,” said a senior Isro scientist. “If the idea was to have an interim chairman, the incumbent could have been given a month’s extension.”