NEW DELHI: Three Atomic Clocks of one of the seven satellites of the country’s newly operational navigation satellite system, also called desi GPS, have stopped working. These rubidium atomic clocks, imported from Europe, are meant to provide precise locational data.

When the time signal is missing, getting true positional accuracy becomes a problem. The initial setback has come at a time when the desi GPS, though operational, is yet to hit the market for commercial purpose. These three atomic clocks, which have stopped working, belong to the first navigation satellite IRNSS-1A.

Indian Space Research Organisation (Isro) had imported 27 sophisticated timekeepers for the nine satellites of the Indian Regional Navigation Satellite System (operational name NaVIC–Navigation with Indian Constellation). Out of which, seven of the satellites are in the orbit and two of them are standby.

Speaking to TOI, Isro chairman A S Kiran Kumar said, “Three atomic clocks of IRNSS-1A have stopped working. But the rest of satellite components are functioning perfectly. In fact, we are using this satellite for messaging activity. The stopping of these atomic clocks has not affected the overall performance of our navigation system. We are targeting to launch the replacement satellite in July.” He rubbished reports that said more atomic clocks have started showing abnormalities. He said, “We are set to launch more navigational satellites. They are in the process of approvals and clearances. We are also making efforts to restart the atomic clocks of IRNSS-1A.”

On the performance of the navigation system, Kiran Kumar said, “NaVIC system is fully operational. Information required for using navigation system is available in public domain. We have started making receiver systems for different applications for using the system. There is one segment of the system which are meant for restrictive services (for military). Towards that also, work is in progress.”

Explaining the significance of these sophisticated clocks, a source in Isro said, “Poor the accuracy of these atomic clocks, less the accuracy of the distance calculated. For the navigation system, minimum of four satellites are needed, but we already have seven satellites in place. Therefore, Isro will give less weightage to the satellite whose atomic clocks have stopped working and depend on the data from other satellites. Therefore, the overall performance will not get affected.”

The source said, “It is not only the atomic clocks of the Indian navigation system that have stopped working, but the clocks in European navigation system Galileo, too, had failed.” In January, the European Space Agency (ESA) had reported that three rubidium atomic clocks and six hydrogen maser clocks on board Galileo had failed.

The Rs 1,420-crore Indian satellite navigation system NavIC consists of nine satellites. Since July 2013, the Indian space agency had launched seven navigation satellites, with each of them having a life span of 10 years. The last one was launched on April 28, 2016.

According to the Indian space agency, the applications of IRNSS are: terrestrial, aerial and marine navigation, vehicle tracking and fleet management, terrestrial navigation for hikers and travellers, disaster management, integration with mobile phones, mapping and geodetic data capture and visual and voice navigation for drivers.