NavIC: How India's Alternative To GPS Is Hanging By A Thread

One of the key lessons India took away from the 1999 Kargil war with Pakistan was the danger of relying on foreign powers for critical strategic support.

In the two and a half decades since, India has worked to build from scratch a capability it lacked during that conflict, and one the United States (US) denied at a crucial moment: a satellite navigation system.

The US Global Positioning System (GPS) was the most advanced satellite navigation system available at the time. India sought access to precise GPS location data to better locate enemy positions but was denied it when it mattered most.

This motivated India to develop what is now called the Navigation with Indian Constellation, or NavIC. India is one of only six entities with their own satellite navigation system, the others being the US (GPS), Russia (Glonass), Europe (Galileo), China (BeiDou), and Japan (QZSS).

But all these years later, has the lesson truly been learnt if India’s independent, indigenously developed system, meant to stand stably on its own feet, is tottering on a single, injured foot, barely holding on?

Three recent revelations, a couple of them damning, over the span of just about a month have brought to light the worrying state of NavIC, previously known as the Indian Regional Navigation Satellite System (IRNSS).

Speaking at Setu 2025, an online Indian Space Research Organisation (ISRO) educational course for school teachers, Nilesh M Desai, Director of the ISRO facility in Ahmedabad, Space Applications Centre (SAC), said NavIC is still some distance away from operationalisation on a regular basis. This is after 11 satellite launches over 12 years, beginning with IRNSS-1A in July 2013.

“NavIC was started after the Kargil war, and we had all the satellites launched by 2016. Of course, some of the satellites have developed some problems. So now we are replacing them. We are still not nearer to operationalisation of NavIC services,” he said, though adding that “in the next couple of years, we are going to hear a lot about NavIC.”

The second and third revelations came a month later, one in response to a Right to Information (RTI) application filed by a long-time space enthusiast, and another via an unstarred question in the Lok Sabha.

The response to his RTI application led the individual behind the “SolidBoosters” account on the social platform X to declare that NavIC was in “an unprecedented crisis” and that “the entire system” is just “one atomic clock failure away from complete operational collapse.”

Further, Union Minister Dr Jitendra Singh revealed in Parliament that of the 11 NavIC satellites launched so far, just four were providing position, navigation, and timing (PNT) services, the very capability NavIC was built to deliver.

Of the rest, four satellites were being used for one-way message broadcast, one had been decommissioned, and two had failed to reach their intended orbits.

These three disclosures, particularly the latter two, paint a dismal picture of a system built to address a major national security gap.

“As you might have noticed, things are not going well,” a former ISRO scientist told Swarajya. “There are reasons for it. The launches have failed for some of the NavIC satellites. One satellite which recently went, the thruster failed; it has gone into an insertion orbit, but from there it’s not going (to the intended orbit). And for some of the satellites which are already inserted, atomic clocks have failed,” he said.

Atomic clocks are an essential part of any accurate navigation system. India uses the Rubidium Atomic Frequency Standard (RAFS) clocks, which are said to be a cost-effective, ultra-high-performance, space-qualified rubidium frequency standard.

“The stability of the atomic clock is very, very high. It will deviate by 1 second in millions of years. Our watch… will drift by a few seconds here and there every day,” Desai explained at Setu 2025. This allows India’s NavIC to provide “5 or 10 metres (m) accuracy from a satellite distance of almost 36,000 km.”

Yet atomic clocks have failed on five of the 11 satellites launched so far. Among the four operational satellites, one, IRNSS-1F, has already suffered failures in two of its three clocks. This was revealed in the RTI response received in early July by SolidBoosters.

“I noticed that the information on NavIC Gen 1 (Generation 1, referring to the IRNSS satellites) had come to a standstill. No new information was forthcoming,” SolidBoosters, who likes to stay anonymous, keeping his public and private lives separate, told Swarajya.

“Then NVS-01 and NVS-02 happened, and NVS-02, as we know, had valve failure, and it was unable to move to the geostationary orbit, where it should be. Then I started to think to myself: Already it’s (NavIC satellites) showing partial failure (in public records like Wikipedia), and since the Indian landmass is big, we need at least four satellites to get the 3D positioning, and that too over a limited area. So I got curious about what happened to the Gen 1 satellites,” he says.

This led him to file an RTI application seeking information about the current state of NavIC satellites. What he learnt was troubling: only four of the 11 launched satellites are currently operational for navigation, namely IRNSS-1B, IRNSS-1F, IRNSS-1I, and NVS-01.

What’s more, IRNSS-1B is in its twelfth year of operation, well past its intended lifespan, and IRNSS-1F is in its tenth. NVS-02, launched earlier this year, is hamstrung by its orbital location. Last we heard was that ISRO was trying to raise the orbit of the NVS-02, but with no success as yet.

The RTI revelation made one thing clear: there is no room for any more failures.

NavIC requires at least four satellites to provide basic PNT services. Why four? Because satellite navigation relies on solving four unknowns: latitude, longitude, altitude, and time. Each satellite provides one equation, and solving all four simultaneously gives accurate position and time information.

Today, NavIC has exactly four satellites providing this data. The bare minimum. And one of them, IRNSS-1F, is already running on its final functioning atomic clock. If that conks off, the entire NavIC system would go down to three satellites.

“Actually, three (satellites) should be good enough,” Desai said, speaking generally, at Setu 2025, with a fourth one “needed to improve the overall accuracy, and because we need timing information also.”

That fourth satellite is critical. The timing error in a receiver, even a microsecond off, causes a 300-metre error in position. The fourth signal allows the receiver to correct its internal clock and ensure reliable positioning.

“If this (the third clock on IRNSS-1F) fails, NavIC drops below the minimum operational threshold and becomes completely unusable,” cautioned SolidBoosters, as per whose estimate, “you need at least seven to eight satellites to get some usable accuracy,” considering the large size of the Indian landmass.

NavIC is designed to have seven satellites operating in a combination of geostationary (GEO) and geosynchronous (GSO) orbits about 36,000 kilometres from Earth, along with a network of ground stations operating round the clock. For its regional navigation purposes, this configuration is adequate, unlike other global satellite navigation systems (GNSS) that use dozens of satellites for global coverage.

There are five satellites in India’s IRNSS series in which all the atomic clocks on board have failed, as revealed in the RTI. These are IRNSS-1A, IRNSS-1C, IRNSS-1D, IRNSS-1E, and IRNSS-1G, each of which carried three atomic clocks.

“When all clocks fail, there is no chance that you can use those satellites for navigation purposes. Currently, they’re just sitting there, doing nothing. You can use them for broadcasting messages. You can send a message, and they will ping you back with the same message,” SolidBoosters says.

For this reason, these five satellites have been repurposed for “navigation messaging services” and “navigation services-related experiments” by ISRO. “This creative reuse cannot mask the fundamental constellation inadequacy,” SolidBoosters said on X.

Interestingly, signals from NavIC satellites are publicly observable using suitable GNSS receivers. SolidBoosters has such a receiver, but it supports only the L1 band — used by GPS, Galileo, Glonass, and BeiDou — and not the bands used by NavIC.

A friend of his with a more advanced receiver capable of tuning into the S band did detect signals from three NavIC satellites, but with weak signal strength.

“We have a term called SNR value: signal-to-noise ratio. GPS can reach 45–50 dB-Hz outdoors, and for BeiDou it’s 30–32 inside my home. He got signals from three NavIC satellites, but at home, the SNR was around 19, and outdoors around 22. For usable signals, it has to be over 25,” SolidBoosters says.

Meanwhile, global systems have factored in plenty of redundancy. China has around 35 BeiDou satellites in orbit, the US 32 for GPS, Europe just under 30 for Galileo, and Russia over 20 for Glonass. These constellations stay operational even when some satellites go down.

It must be said that India’s seven-satellite constellation, spread across geostationary and geosynchronous orbits, is sufficient to cover the entire country and its surroundings, as planned. With this configuration, it can achieve a position accuracy better than 5 metres and a timing accuracy better than 20 nanoseconds, boasting a performance similar to the world leader GPS.

But what is up with the clock failures on India’s NavIC satellites?

ISRO has conducted the “root cause analysis” for the RAFS clock failures on the IRNSS satellites but refused to divulge any details since it is “vital technical information,” the sharing of which would go “against the scientific interests of the nation.”

“With satellites, you can expect failures. It’s not that nobody fails. Everybody fails. And it’s a learning process. I asked them what led to the failure of the clocks, but they denied the information. I asked for a root cause analysis, but they said they can’t share it. I don’t know whom they are trying to save... themselves or the group that supplied the clocks,” SolidBoosters said.

The failed clocks were all imported. Swiss firm SpectraTime is a major supplier of these high-precision atomic clocks, which are also used in Europe’s Galileo constellation, where they failed as well.

The clock “failures all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground, with investigations continuing to identify a root cause,” the European Space Agency said, adding: “Continuing investigations on the ground have identified potential weaknesses in the RAFS clock design, but no root cause has yet been established.”

A former ISRO engineer was blunt. “I am sorry; if you depend on Swiss atomic clocks for a strategic GPS (GNSS) system, then, of course, you are setting yourself up for failure. The clocks that failed were not Indian. Let’s be clear about that. The clocks that failed were Swiss,” he told Swarajya on the condition of anonymity.

“And they just didn’t fail in India. They failed on the Galileo constellation also. But unlike us, the Galileo constellation was immediately refreshed, and new satellites were sent out very quickly. In our case, our launch cadence was not good enough to replace these satellites fast enough to maintain operational capability,” the engineer said.

Indeed, India’s launch cadence has slowed. Between early 2024 and mid‑2025, only seven launches took place, far below the projected 12 to 30, with one failure and one partial failure.

In June 2025, the PSLV-C61 mission carrying Earth-observation satellite EOS‑09 failed during its third stage, reportedly due to a drop in chamber pressure. In January, the Geosynchronous Satellite Launch Vehicle (GSLV) carrying NVS-02 failed to reach its intended orbit due to stuck oxidiser valves. The agency has been trying to use the satellite for navigation from its elliptical orbit.

This partial failure was costly. If NVS-02 had succeeded, NavIC would now have five satellites, allowing room to lose one due to age. For now, says SolidBoosters, NVS-02 can provide PNT services for two to three hours per day, but this requires additional software and hardware changes on the user side.

“Presently, NavIC is in a very sorry state,” the former ISRO engineer said. “Honestly, there needs to be a national effort and a national mission to improve it. Things are moving but not fast enough. The people at ISRO are very hard-working. And they are trying their level best. But there are supply chain disruption issues, and coming up with a new atomic clock in India should have been done long ago, but we are doing it now,” he says.

“Why are we in India not encouraging startups to construct space-qualified and portable atomic clocks?” asks Chaitanya Giri, a Fellow at the Observer Research Foundation's Centre for Security, Strategy and Technology with a focus on India's space ecosystem.

“No foreign VC (venture capitalist), even the best ones operating in the Indian startup ecosystem, are going to fund atomic clock innovation in India. They are high on the export controls list. Rather, in today’s scenario of tariffs and trade wars, it (the atomic clock) may even be denied to us. But why did it not make it into any of the Indian government’s startup Grand Challenges? This is a distressing question,” he says.

India debuted its indigenous atomic clock, designed and developed at SAC over almost 10 years, in the NVS-01 launch in 2023. “They put four clocks on that, and one was an indigenous clock, which is the primary clock on the satellite,” SolidBoosters said. An indigenous clock also flew on the NVS-02.

The silver lining, if you will, is that the India-made atomic clocks have not failed. In response to a different RTI petition filed by SolidBoosters, who has been filing RTIs regularly since 2023, the performance of the India-made clock on NVS-01 was reported to be satisfactory. The indigenous clock will be used on all future NavIC satellites.

Still, with just four satellites operating, and one on its last functioning clock, India stands on the edge of losing its navigational autonomy.

It should never have come to this, not after Kargil.

And it is not just space. “Why is it that 85 per cent of our Indian frontline aircraft by 2036 will be flying on American engines?” the former ISRO engineer asked. “Have we forgotten the lessons of 1998? If we haven’t, would you have a single point of failure for 85 per cent of your fleet?”

“Space cannot be seen in isolation. There should be a national mission for IRNSS. For engines. For quantum computing. Some of that is happening, but it is not moving fast enough.”

A former ISRO scientist, who also didn’t want to be named, similarly says, “It all depends on the importance that the government is giving to the programme. See, for me, it is very clear that NavIC is essential. Or else, we are always diplomatically dependent on others. Just imagine if GPS is not there; none of these cab apps or delivery apps, and so on, nothing would work on the commercial side. Anyway, defence would come to a standstill. I mean, we are essentially dependent entirely on an infrastructure created by non-Indian actors. So it is time that we should come out of it,” he says, adding, “The only thing is how the bureaucracy will fix it is the question.”

The need to loosen GPS’ grip over our lives was underlined by Desai at Setu 2025, as he made a pitch for increased adoption of NavIC. “When you wake up in the morning and sleep at night, within that time period, almost 90 per cent of the activities which we do are influenced or governed or controlled or in some way influenced by the navigation system. And by navigation system all across the world, almost 90 per cent of the navigation happens through GPS signals. So you are governed indirectly by GPS… instead of that, we’ll urge you that we should be governed by our own country’s system, that is NavIC.”

NavIC has wide-ranging uses, from aviation and maritime navigation to personal mobility, surveying, agriculture, search and rescue, and emergency alerting. Over 8,700 Indian trains already use NavIC for real-time tracking.

More than 100 phone models are NavIC-ready. The introduction of L1 band support on NVS-01 now allows NavIC to be compatible with standard GPS chips, removing a major roadblock to mass adoption.

“We made an initial mistake of not going for this chip development on our own. Because the GPS chips are not usable (for NavIC). For other systems, (such as) Glonass or BeiDou or Galileo, they have the advantage that they can easily use GPS chips because their signals are similar. But in our case, the signals were in totally different frequency bands. So we had to ab initio design our antenna system, our RF (radio frequency) system, and our processing system. Everything we had to do on our own. And that is why it took time to put that receiver chip into the mobile,” Desai revealed in his Setu 2025 talk.

For the longest time, NavIC operated in the L5 band (1176.45 MHz) and S band (2492.028 MHz). But starting with NVS-01, the L1 band (1575.42 MHz) was introduced, making it compatible with the GPS signal. So a GPS chip can also be used to develop an L1 band NavIC receiver.

L and S bands are earmarked for navigation activities worldwide. The United Nations (UN) agency International Telecommunication Union allocates frequency in these two bands.

Besides the civilian mode, called the Standard Positioning Service (SPS), which allows anybody to tap into NavIC, India’s regional navigation system has a Restricted Service mode meant for use by the Indian armed forces. This is similar to how GPS has part of its services reserved for the US military.

ISRO has also developed prototype receivers for the military. Over time, the technological know-how will be handed over to the industry so that they can develop these military-grade receivers.

India’s space agency has also been considering whether to keep NavIC regional or to make it global. India's growing global footprint suggests that NavIC's ambitions should match the country's expanding horizons.

Former ISRO chairman S Somanath was convinced that NavIC should go global. In order to do so, the size of the constellation as well as the diversity of orbits would have to be increased.

“We have reasonably concluded that we need to have a combination of GEO-MEO constellation to be maintained for giving services within this country and possibly expand it to a global constellation at a later point in time with lesser expenses,” Somanath said in his Engineer’s Day Special Lecture at the Indian Institute of Astrophysics, Bengaluru, in September 2022.

While GEO refers to the geostationary orbit, MEO stands for the middle-earth orbit, which claims a wide range of space from 2,000 km above Earth all the way up to about 36,000 km. As many as 24 to 30 satellites will have to be launched into MEO over and above the existing geostationary constellation in order to provide global coverage, as per ISRO’s estimate.

If at some point India moves towards global coverage, it would certainly have to go beyond the current seven-satellite constellation. ISRO is known to be exploring emerging technologies like low-earth orbit (LEO) PNT systems, which offer distributed navigation architectures that could serve as the foundation for truly global coverage. Since LEO constellations operate closer to Earth, they can provide stronger signals and better coverage in challenging environments like polar regions.

Going global, or even growing stronger regionally, will require a significant expansion of the ground segment, which includes control and monitoring stations. This would improve India’s navigation accuracy, which depends not just on satellites but also on the density of ground-based monitoring and ranging stations that track satellites and provide corrections. NavIC operates with a network of 21 ranging stations across India, while BeiDou has more than ten times as many monitoring stations around the world than even GPS does.

But for any of this to happen, India first needs a functional constellation of seven satellites in the correct orbits.

Three second-generation NavIC satellites — NVS-03, 04, and 05 — are due for launch later this year and next. These promise to augment and stabilise the existing constellation.

But ISRO will need to get every one of them right and hope the ageing atomic clocks on the Gen 1 satellites can hold the line just a little longer.