NavIC - the Indian GPS Goes Limited, Needs New Satellites Soon

NavIC (Navigation with Indian Constellation) or IRNSS (Indian Regional Navigation Satellite System) has got a major setback, as it's services have became limited. In a written reply in the Lok Sabha, Union Minister of State for Space Dr Jitendra Singh said only three satellites in the NavIC constellation are presently capable of providing Positioning, Navigation and Timing (PNT) services. 

To provide basic positioning service, a minimum of 4 operational satellites are required in orbit. Hence, the NavIC constellation with 3 active satellites cannot provide standalone positioning service; however, timing service is functional. 

However Indian government said users are not facing operational vulnerabilities because NavIC is now used alongside other global satellite navigation systems in a multi-constellation Global Navigation Satellite System (GNSS) environment as receivers to combine signals from GPS, Galileo, GLONASS and NavIC for navigation. 

After being rejected for requesting GPS data by America (USA) during Kargil war in 1999, India commissioned IRNSS in May of 2006 with an initial cost of $174 million. 

Primary Drivers for the Project

• Strategic Sovereignty: India needed an un-jammable, independent navigation system for its military, missiles, and aircraft during geopolitical conflicts.
• Guaranteed Reliability: Foreign GPS providers can degrade or turn off their signals over specific regions during a crisis, a risk India could no longer accept.
• National Security: The system provides encrypted, high-precision data reserved exclusively for the Indian Armed Forces and strategic government agencies. 

In fact real significance of NavIC was celebrated during the May 2025 cross-border counter-terror operations (code name: Operation Sindoor) following the Pahalgam attack, NavIC provided the Indian Armed Forces (Army & Air Force) with high-precision geolocation data to execute surgical strikes deep inside hostile territory.

The first satellite, IRNSS-1A was launched on 1st July, 2013. During 2013-2018 ISRO has launched 8 satellites to space, last one IRNSS-1I replaced IRNSS-1A. In April 2016 constellation was completed and named NavIC by Prime Minister Narendra Modi. But the system became operational for public and strategic use in 2018. In Phase I of NavIC, out of 9 launched satnav satellites, 8 went to their orbits – that’s huge success (88.88%). 

NavIC - Phase I Satellites: 

Satellites (All have 10-year design mission life)	Launch Date	Launch Vehicle	Present Status
IRNSS-1A	2013-07-01	PSLV-XL-C22	Launch was successful. Rubidium atomic clocks (supplied by Swiss company SpectraTime) failed – first failure found in July 2016. By January 2017 all three clocks failed – rendering its navigation and positioning capabilities non-functional. Being used for one-way short message broadcast messaging and emergency societal alerts.
IRNSS-1B	2014-04-04	PSLV-XL-C24	Launch was successful. Operational.
IRNSS-1C	2014-10-16	PSLV-XL-C26	Launch was successful. Atomic clocks failed. Being used for one-way short message broadcast messaging and emergency societal alerts.
IRNSS-1D	2015-03-28	PSLV-XL-C27	Launch was successful. Decommissioned after life span of 10 years in July 2025.
IRNSS-1E	2016-01-20	PSLV-XL-C31	Launch was successful. Atomic clocks failed. Being used for one-way short message broadcast messaging and emergency societal alerts.
IRNSS-1F	2016-03-10	PSLV-XL-C32	Launch was successful. Atomic clocks failed. Being used for one-way short message broadcast messaging and emergency societal alerts.
IRNSS-1G	2016-04-28	PSLV-XL-C33	Launch was successful. Replaced by NVS-01. Being used for one-way short message broadcast messaging and emergency societal alerts.
IRNSS-1H	2017-08-31	PSLV-XL-C39	Planned to replace IRNSS-1A. Launch was failed as payload fairing failed to separate and satellite could not reach the desired orbit.
IRNSS-1I	2018-04-12	PSLV-XL-C41	Launch was successful. Operational – replaced IRNSS-1A.

 

Differences from other satnav systems:

ISRO made NavIC to use L5 and S1 frequency while others (GPS, Galileo, GLONASS, BeiDou) uses L1 mostly (and L5 too). Thus NavIC is not supported by older devices (which supports mostly L1 band). 

NavIC was specifically custom-tailored by ISRO to cover the Indian subcontinent and up to 1,500 km beyond its borders, it incorporates design choices that outperform global systems when used within its target footprint. NavIC provides superior localized accuracy, reliability, and precision over India and the surrounding South Asian region. 

NavIC transmits simultaneously over dual frequencies (L5 and a unique S-band). By measuring the live difference in delay between these two distinct bands, a NavIC receiver calculates the exact atmospheric error in real-time without relying on predictive models, yielding superior positioning accuracy (under 5 metres vs. GPS's 5–20 metres).

NavIC places its constellation in Geostationary (GEO) and Geosynchronous (GSO) orbits fixed over the Indian subcontinent. Because these satellites move at the exact speed of Earth’s rotation, they appear stationary from the ground. They are permanently visible to the receiver at all times, making them exceptionally stable. NavIC's dedicated S-band frequency is highly resistant to this urban reflection, allowing quick, reliable mapping in narrow streets and also in thick forests, plantations, or tree-lined roads. 

Tech Glitches Hit NavIC 

In all phase I of NavIC satellites ISRO equipped three Rubidium Atomic Frequency Standard (RAFS) clocks (one primary and two backups), supplied by SpectraTime, a specialized precision clock manufacturer based in Neuchâtel, Switzerland (now a subsidiary of the French aerospace and defense group Safran). Since July 2016, when IRNSS-1A’s clocks failed, SpectraTime-supplied clocks on European Space Agency's (ESA) Galileo navigation system also faced similar technical issues. In 2021 Galileo opted Orolia to supply atomic clocks for their second generation satellites. 

ISRO traced the malfunction to a technical glitch in a feed-through capacitor that carried the DC power supply to the clock’s physics package, which failed due to excessive temperature spikes.

With all 3 clocks failed, a satellite lost its ability to assist in Positioning, Navigation, and Timing (PNT) calculation. However, ISRO did not completely retire the satellites; instead, they were repurposed to provide one-way broadcast messaging and emergency societal alerts. ISRO attempted to replace the IRNSS-1A with IRNSS-1H, but the mission failed to insert the satellite into the desired orbit. 

Phase II of NavIC - NVS Series of Satellites

Subsequently, ISRO began to rebuild the core 7-satellite constellation and restore complete strategic independence. ISRO has transitioned entirely to indigenous rubidium atomic clocks developed at the Space Applications Centre (SAC) in Ahmedabad for phase 2 of NavIC with NVS series of satellites. Thus ISRO removed supply chain bottlenecks, high import costs, and export control regulations for atomic clocks.

There is an indigenous ACMU (Atomic Clock Monitoring Unit) subsystem which acts as the "brain" of the navigation payload by generating a 10.23 MHz Master Timing Reference. It features a built-in phase meter and fine-tuning steps that can automatically detect and correct frequency drifts in real time without degrading performance (frequency stability - Ultra-high (~5 × 10⁻¹² at 1 sec, dropping to 5 × 10⁻¹⁴ over 10k sec); frequency drifts - less than 5 × 10⁻¹³ per day). Bypassing these thermal and electrical vulnerabilities allowed ISRO to extend the mission life of the NVS generation from 10 years to 12 years.

On 29th May, 2023 ISRO sent NVS-01 to orbit - this satellite also supports band L1 for low power devices. On 29th January 2025, ISRO attempted to sent NVS-02 to replace IRNSS-1E but suffered from a propulsion system failure. 

NavIC Satellites, as seen by GPSTest app on Android - 1B, 1C, 1F, 1I and NVS-01 are connected. (November 2023)

Experts believe ISRO and the government have been distracted by missions such as Gaganyaan and the Axiom Mission 4, which involved Shubhanshu Shukla going to the International Space Station — the first Indian to do so.

Back in July 2025, in a response to RTI, Govt. of India informed that only 4 satellites of NavIC are providing core PNT (position, navigation & timing) services. Of these 4, 1 has completed end of planned life (1B) and 1 has partial equipment failure (1F). Other two are: 1I and NVS-01. 

But on 13th March 2026, when the final working atomic clock on IRNSS-1F gave out, dropping the NavIC fleet below the 4 active satellites required to provide navigation services. At present the three active NavIC satellites are: 1B, 1I, NVS-01. 

ISRO has plans to launch next satellites soon to re-complete NavIC constellation.