NavIC Atomic Clock Failure: Impact on India’s GPS Ambitions Explained

NavIC Atomic Clock Failure Latest News

• India’s regional navigation system NavIC has faced another setback after the atomic clock onboard the IRNSS-1F satellite stopped functioning, leading to the loss of its positioning data.
• Although the satellite will still provide messaging services, atomic clocks are essential for accurate navigation signals used in mapping, vehicle navigation, and infrastructure planning. 
• The issue is compounded by the NVS-02 replacement satellite failing to reach its final orbit, further affecting the system’s positioning capability.

About IRNSS or NavIC

• The Indian Regional Navigation Satellite System (IRNSS), also known as Navigation with Indian Constellation (NavIC), is India’s satellite-based navigation system designed to provide positioning services over India and up to 1,500 km beyond its borders.
• NavIC was planned as a seven-satellite constellation, similar in concept to the U.S. Global Positioning System (GPS), to deliver reliable navigation and timing information across the region.
• When fully operational, NavIC is designed to provide location accuracy of about 10 metres over India and neighbouring areas. 
• Because its satellites are positioned directly above the region, signals are stronger and more reliable in challenging terrains such as valleys and forests.
• Despite its strategic importance, the NavIC system has faced technical issues since its inception, affecting the consistent availability of accurate positioning services.

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Status of NavIC Satellites Providing Positioning Data

• After the 2023 launch, five satellites in the NavIC constellation were capable of providing positioning data: IRNSS-1B, IRNSS-1C, IRNSS-1F, IRNSS-1I, and NVS-01 (a new-generation NavIC satellite).
• With the failure of the atomic clock on IRNSS-1F, the satellite can no longer provide positioning data, reducing the number of operational satellites in the system.
• Many early NavIC satellites are approaching or exceeding their design life.
  • IRNSS-1A (2013) is almost defunct due to earlier atomic clock failures.
  • IRNSS-1B and IRNSS-1C, launched in 2014, have also crossed their 10-year mission life.
• ISRO attempted to maintain the constellation through replacement missions:
  • IRNSS-1H (2017) failed to reach orbit after the heat shield did not open.
  • IRNSS-1I (2018) was successfully launched later as a replacement satellite.

NVS-02 Satellite and Its Failure

• NVS-02, the second satellite of the new-generation NavIC series, was launched in January 2025 aboard GSLV-F15 during ISRO’s 100th mission and placed in a highly elliptical transfer orbit.
• The satellite failed to move into its intended operational orbit due to an electrical malfunction that prevented the engine from igniting.
• A review committee found that the signal required to activate the pyro valve in the oxidiser line did not reach the engine. 
  • This likely occurred because a connector contact disengaged, breaking the electrical circuit.

Delays in Developing the User Segment

• The NavIC programme has also faced criticism for delays in developing user receivers. 
• A 2018 CAG report noted that although funding was approved in 2006, work began only in 2017, by which time several satellites had already been launched.
• Despite these setbacks, NavIC services are already used in aviation, shipping, and railways, and many modern smartphones support NavIC signals alongside GPS and GLONASS.

Advancements in New-Generation NavIC Satellites

• Indigenous Atomic Clocks – A key upgrade is the development of indigenous atomic clocks by ISRO, reducing dependence on foreign systems and addressing earlier failures that affected positioning accuracy.
• Importance of Atomic Clocks – Satellite navigation relies on precise time measurement to calculate location. Failures in atomic clocks previously disrupted accurate positioning, making this upgrade crucial for reliability.
• Extended Mission Life – The new-generation satellites have an extended lifespan of 12 years, compared to 10 years for earlier satellites, ensuring longer operational stability.
• Addition of L1 Frequency Band – Along with existing L5 and S bands, new satellites transmit in the L1 frequency, which is widely used by global systems like GPS.
• Improved Interoperability and Usability – The inclusion of the L1 band enhances compatibility with global navigation systems and enables usage in low-power devices like smartphones and smartwatches, expanding NavIC’s applications.

Global Satellite Navigation Systems

• There are four primary global navigation satellite systems (GNSS):
  • US – GPS (Global Positioning System)
  • Russia – GLONASS
  • Europe – Galileo
  • China – BeiDou
• These systems provide worldwide positioning, navigation, and timing services.

Regional Navigation Systems

• Some countries operate regional systems:
  • India – NavIC (IRNSS) with 7 satellites
  • Japan – QZSS (Quasi-Zenith Satellite System) with 4 satellites, mainly augmenting GPS over Japan

Orbital Configurations

• GPS, GLONASS, Galileo: Over 20 satellites each in Medium Earth Orbit (~20,000 km)
• BeiDou: Over 40 satellites in mixed orbits (Medium Earth + Geosynchronous ~35,000 km)
• India and Japan systems: Fewer satellites placed in Geosynchronous orbits, optimised for regional coverage
• Global systems ensure worldwide coverage, while regional systems like NavIC and QZSS are designed for higher accuracy within specific geographic areas.

Source: IE | WION