India’s indigenous satellite navigation system NavIC (Navigation with Indian Constellation) has encountered a significant setback after one of its operational satellites stopped functioning properly. The satellite IRNSS-1F, launched in 2016, recently suffered a failure after its last working atomic clock stopped functioning, according to officials from the Indian Space Research Organisation (ISRO).
This incident has reduced the number of fully operational satellites providing navigation services, raising concerns about the reliability and continuity of India’s regional navigation network.
IRNSS-1F Satellite Fails After Completing 10-Year Mission Life
The IRNSS-1F satellite, launched on March 10, 2016, completed its planned mission life of ten years earlier this month. However, on March 13, 2026, the satellite’s final functional atomic clock malfunctioned, making it unable to continue providing Positioning, Navigation, and Timing (PNT) services.
ISRO confirmed that although the atomic clock has stopped working, the satellite will still remain operational in orbit for one-way broadcast messaging services used for certain public applications.
Each NavIC satellite carries three atomic clocks, which are critical for accurately calculating signal travel time between the satellite and Earth. These calculations determine the user’s exact position on the ground. Even small timing errors can lead to location inaccuracies of hundreds of kilometres.
NavIC Requires At Least Four Operational Satellites
India’s NavIC system needs a minimum of four fully functional satellites to provide reliable navigation services for both civilian users and government agencies.
These services are used for:
- Railway tracking systems
- Military navigation and targeting
- Disaster management
- Vehicle tracking and fleet management
- Maritime navigation
- Mobile and location-based services
After the IRNSS-1F failure, only three satellites remain capable of providing full navigation services:
- IRNSS-1B
- IRNSS-1L
- IRNSS-1J (NVS-01)
This drop below the required threshold could potentially affect location services provided by the NavIC network.
Majority of NavIC Satellites Have Faced Technical Issues
Since 2013, ISRO has launched 11 satellites under the NavIC programme. However, several of them have encountered technical problems over time.
According to government data shared in Parliament:
- 4 satellites were providing PNT navigation services
- 4 satellites were used only for messaging services
- 1 satellite was decommissioned after completing its mission life
- 2 satellites failed to reach their intended orbit
With the latest failure, six satellites in the NavIC constellation have experienced atomic clock malfunctions, highlighting a recurring technical challenge.
Previous satellites affected by atomic clock failures include:
- IRNSS-1A (2013)
- IRNSS-1C (2014)
- IRNSS-1D (2015)
- IRNSS-1E (2016)
- IRNSS-1G (2016)
Most of these failures were linked to defective imported atomic clocks, which were originally sourced from European suppliers.
Importance of Atomic Clocks in Satellite Navigation
Atomic clocks are the core technology behind all satellite navigation systems, including GPS, GLONASS, Galileo, and NavIC.
They allow satellites to transmit signals with extremely precise time stamps, enabling receivers on Earth to calculate their distance from multiple satellites simultaneously.
If these clocks malfunction:
- Timing accuracy is lost
- Signal calculations become unreliable
- Position data can become severely distorted
Because of this, maintaining highly reliable atomic clocks is crucial for any satellite navigation network.
NavIC: India’s Strategic Alternative to GPS
India began developing its own satellite navigation system after the 1999 Kargil War, when access to foreign GPS data was restricted during military operations.
The result was the Indian Regional Navigation Satellite System (IRNSS), later branded as NavIC.
Key objectives of NavIC include:
- Reducing dependence on foreign navigation systems
- Providing accurate navigation across India and nearby regions
- Supporting defence operations
- Improving transportation and infrastructure monitoring
The system is designed to cover India and a region extending about 1,500 km beyond its borders.
Other Challenges in the NavIC Programme
Apart from satellite failures, the programme has also faced issues related to launch vehicle anomalies and orbital problems.
Two satellites failed to reach their intended orbit:
- IRNSS-1H (2017)
- IRNSS-1K / NVS-02 (2025)
In the case of the NVS-02 satellite, ISRO’s investigation revealed that the orbit-raising engine did not receive the drive signal needed to activate the pyro valve, preventing the satellite from reaching its final operational orbit.
Additionally, the PSLV launch vehicle, which is the workhorse rocket for NavIC missions, experienced two launch anomalies in 2025–2026, delaying planned satellite deployments.
Future NavIC Satellites Planned
To strengthen the navigation network, ISRO has planned to launch three second-generation satellites:
- NVS-03
- NVS-04
- NVS-05
These satellites are expected to feature:
- Improved atomic clock systems
- Enhanced navigation capabilities
- Greater reliability for long-term service continuity
However, launch delays caused by recent rocket anomalies have pushed back the original timelines.
Impact on Services Like Railway Tracking
NavIC plays a critical role in India’s transportation infrastructure. The government previously announced plans to use the system for real-time monitoring of approximately 12,000 trains across the country.
According to official data:
- Around 8,700 trains are already equipped with NavIC receivers, combined with other global navigation systems.
Any disruption in NavIC’s operational satellites could affect these services, although integration with other GNSS systems provides partial backup.
The failure of IRNSS-1F highlights ongoing technical challenges within India’s NavIC navigation programme, particularly related to atomic clock reliability and satellite deployment delays. With only three fully operational satellites currently available for navigation services, ISRO will need to accelerate the launch of next-generation satellites to maintain the stability and independence of India’s indigenous navigation system.
Strengthening NavIC remains strategically important for national security, transportation, and technological self-reliance, making the upcoming satellite launches crucial for the future of India’s space-based navigation capabilities.
