India’s homegrown satellite navigation system, NavIC (Navigation with Indian Constellation), is in serious trouble. The Indian Space Research Organisation (Isro) has confirmed that IRNSS-1F, a satellite launched in March 2016, completed its 10-year design life on March 10 this year, and that the on-board atomic clock had stopped functioning.
The satellite will continue to orbit and send one-way broadcast messages, but it can no longer help anyone navigate. That one failure has pushed NavIC below the minimum threshold it needs to function as a navigation system.
You need at least four satellites working in tandem to calculate a position on Earth. India now has three.
WHICH THREE NAVIC SATELLITES REMAIN FUNCTIONAL?
The three satellites still providing navigation services are IRNSS-1B, launched in April 2014, IRNSS-1L, launched in April 2018, and NVS-01, the first of the second-generation NavIC satellites, launched in May 2023. IRNSS stands for Indian Regional Navigation Satellite System.
Of these, IRNSS-1B has already crossed its 10-year design life and is running on borrowed time. NVS-01 is the youngest and healthiest of the three, but one satellite cannot carry a navigation system on its own.
WHAT IS AN ATOMIC CLOCK AND WHY DOES IT MATTER?
An atomic clock is the beating heart of any navigation satellite. It measures time by tracking the natural vibrations of atoms with extraordinary precision. When a signal travels from a satellite to your phone, the clock calculates exactly how long that journey took.
A billionth of a second’s error can push your calculated position off by hundreds of metres. Without a working clock, a navigation satellite is useless.
For the first time in the NavIC programme, an indigenous atomic clock was flown aboard NVS-01 (Navigation Satellite 1), the first of the second-generation satellites launched in May 2023.
Earlier satellites relied on imported clocks, and that dependence proved to be a persistent weak point.
HOW DID NAVIC END UP IN THIS MESS?
As of July 2025, of the 11 NavIC satellites put into orbit, four were providing Position, Navigation and Timing (PNT) services, four were being used only for one-way message broadcast after losing navigation capability, one was decommissioned after end-of-life, and two could not reach their intended orbits.
The IRNSS-1F failure on March 13, 2026 has now reduced the PNT count from four to three.
NavIC is designed with a constellation of seven satellites. The system is a long way from that target.
WHAT HAPPENED TO THE REPLACEMENT SATELLITE NVS-02?
NVS-02 launched in January 2025 but never made it to its intended orbit. A tiny electrical fault stopped its engine from firing at exactly the wrong moment, leaving the satellite stranded. It cannot provide any navigation services, and remains out of action.
Isro implemented corrective actions in subsequent missions. The fixes were applied to the CMS-03 spacecraft launched in November 2025, placing the satellite in its intended orbit.
WHEN WILL NAVIC BE BACK ON ITS FEET?
In July 2025, Union Minister of State for Science and Technology and Earth Sciences Dr Jitendra Singh told the Lok Sabha in a written reply that NVS-03 would launch by the end of 2025, with NVS-04 to follow after six months. NVS-03 has not launched yet, meaning the schedule has slipped.
The new NVS satellites also bring a welcome upgrade. They support the L1 band, which means future smartphones could work with NavIC without needing extra hardware, just a software update.
On the ground, around 8,700 trains already use NavIC for real-time tracking, and the target is 12,000. The system also supports disaster alerts, marine navigation, and vehicle tracking.
With only three satellites left, all of this is now at risk. The clock is ticking in more ways than one.
