In this image, the NavIC (Navigation with Indian Constellation) and GPS (Global Positioning System) logos are shown on the map along with the satellite model. File | Photo credit: Reuters
The last atomic clock on board the Indian Regional Navigation Satellite System (IRNSS)-1F of the Indian Space Research Organization (ISRO) has failed, ISRO said in a statement. This further weakens the country’s original “GPS” system, informally called NavIC.
Atomic clocks are essential for satellites to offer position, navigation and timing services. Since the launch of the first of eight satellites in the IRNSS system in 2013–2018, the government has encouraged Indian businesses, including computer and electronic goods manufacturers, that have timing services to rely on NavIC to determine Indian Standard Time.
Currently, the reference standard for these purposes is the American Global Positioning System (GPS) with its 30 satellite systems.
“On March 13, 2026, the purchased on-board atomic clock ceased to function. However, the satellite will continue to operate in orbit for various societal applications to provide one-way message services. The IRNSS-1F satellite, launched in March 2016, completed its design life of 10 years on March 10, 2026.”
Since 2013, nine IRNSS satellites have been launched. Eight of them reached their intended orbit. The last of this constellation of satellites (IRNSS-1I) was launched in 2018. While equivalent US, Chinese and European systems provide global positioning services, NavIC is expected to do so only within India and within a radius of 1,500 km. However, this is seen more as a backup system in case of future global conflicts where India is denied access to these foreign constellations.
In July 2025, ISRO revealed through a Right to Information request that five NavIC satellites were completely out of order, with all three clocks on each satellite not working. In one of the three satellites with working atomic clocks, two of the three clocks failed.
The atomic clocks in this constellation of satellites were imported by ISRO from SpectraTime, a Swiss manufacturer of high precision atomic clocks. Four operational satellites can be relied upon to provide positioning and navigation services, Union Minister for Space Jitendra Singh told Parliament. With the failure of the IRNSS-1F clock, their number was reduced to three.
For the next batch of satellites to replace the damaged and aging fleet of IRNSS satellites – two of the three satellites in use have already passed their nominal shelf life of 10 years, although it is possible that these systems will continue to operate beyond this time – ISRO has decided to install indigenously developed rubidium clocks.
One replacement satellite, NVS-01 launched in May 2023, contains the originally developed rubidium (atomic) clock. The second, the NVS-02 satellite, launched in January 2025, failed to reach its intended orbit.
ISRO had earlier said that it will launch at least three satellites by the end of 2026 to replace non-functional and aging satellites.
Published – 14 March 2026 19:38 IST
