India’s NavIC satellite navigation system is in distress with only three functional satellites

New Delhi, March 17: Nearly three years after India’s maiden second generation navigation satellite was placed in the orbit, the rest of such satellites are way behind their scheduled launch dates even as only two of the nine first generation NAVIC satellites remain functional, crippling the Indian Regional Navigational Satellite System.

First of the new lot, NVS-01, was placed in the orbit in May 2023. The second one, NVS-02, was launched 19 months later in January 2025. The NVS-02 mission, however, failed as the satellite didn’t reach the intended orbit.

The third satellite NVS-03 was planned for a 2025 launch followed by NVS-04 and NVS-05 in 2026. But none of the launches happen and no new launch schedules were fixed for the five second generation navigation satellites to replace the IRNSS satellites, sources said.

Six of the nine older generation IRNSS satellites have stopped providing the navigation services as 18 on-board atomic clocks – three in each satellite – stopped working before their designated lives, sources said. The clocks were purchased from a Swiss company.

In a brief statement, ISRO last week said the on-board atomic clocks of IRNSS-1F stopped functioning on March 13, ten years after the satellite was launched.

Earlier all the three atomic clocks of IRNSS-1A, 1C, 1D, 1E and 1G turned defunct, making the satellites useless for PNT (position, navigation and timing) services.

This effectively leaves only three navigation satellites – IRNSS-1B, 1I and NVS 01 - in orbit, adversely impacting the quality of the service.

Conceived as a regional navigation service for military and civilian applications, the NAVIC (navigation with Indian constellation) system covers the entire Indian region and areas extending up to 1,500 km around the country on dual frequencies in L5 and S bands. These are radio-frequency bands used in satellite navigation communication.

The NVS series of satellites was realised to continue with legacy services while adding new features for wider applications such as civilian L1 signal and indigenous atomic clock. The atomic clocks for NVS-01 and 02 were made at Space Application Centre, Ahmedabad.

DH questions to ISRO on the reasons for failure of imported atomic clocks haven’t elicited any response till the time of filing the report.

ISRO officials have always not only batted for sovereign satellite constellations to PNT services given the current geopolitical realities, but also favoured expansion of the constellation.

However, research into next generation clocks needed in navigation satellites like optical clocks has made a slow start as key funding proposals to develop such clocks indigenously were pending for approvals at Department of Science and Technology and Department of Space, sources told DH.

Globally, at least five countries have their own fully operational navigation systems – GPS of the US, GLONASS of Russia, Galileo (European Union), BeiDou (China) and QZSS (Japan).