NavIC and Atomic Clock Failure in IRNSS-1F
Why in news
The atomic clock on IRNSS-1F has stopped functioning, weakening India’s indigenous navigation system NavIC, developed by the Indian Space Research Organisation.
What happened
On 13 March 2026, the last working atomic clock on IRNSS-1F failed.
Atomic clocks are essential for precise timing signals, which are required for positioning and navigation.
With this failure, the number of NavIC satellites capable of providing navigation services dropped to three, while at least four satellites are required for reliable navigation.
About NavIC (Navigation with Indian Constellation)
Feature | Details |
Developed by | ISRO |
Operational name | NavIC |
Satellite system | Indian Regional Navigation Satellite System |
Coverage | India and up to 1500 km beyond Indian borders |
Purpose | Positioning, navigation and timing services |
Launch period | 2013–2018 (initial constellation) |
Key point:
Unlike global systems, NavIC is a regional navigation satellite system.
Role of atomic clocks in navigation satellites
Atomic clocks provide ultra-precise time measurement, which allows satellites to determine a receiver’s location.
Working principle:
Satellite sends time-stamped signals.
Receiver calculates signal travel time.
Distance from satellite is determined.
Position is calculated using signals from multiple satellites.
Without functioning atomic clocks, accurate positioning becomes impossible.
Problems in the NavIC constellation
Nine satellites launched since 2013.
Eight reached intended orbit.
Several satellites became defunct due to atomic clock failures.
RTI disclosures (2025):
Five satellites completely non-functional (all clocks failed).
One satellite had two clocks failed.
Now only three satellites with working clocks remain.
Replacement satellites
India has begun launching second-generation NavIC satellites (NVS series).
Satellite | Status |
NVS-01 | Launched May 2023 with indigenous rubidium atomic clock |
NVS-02 | Launched Jan 2025 but failed to reach intended orbit |
ISRO plans to launch at least three replacement satellites by 2026.
Shift to indigenous atomic clocks
Earlier NavIC satellites used clocks imported from SpectraTime.
Future satellites will use indigenously developed rubidium atomic clocks, improving:
technological self-reliance
reliability of navigation infrastructure
Comparison with global navigation systems
System | Country/Region | Coverage |
GPS | USA | Global |
BeiDou | China | Global |
Galileo | European Union | Global |
NavIC | India | Regional (India + 1500 km) |
Prelims Practice MCQs
Q. With reference to NavIC, consider the following statements:
NavIC provides global navigation coverage similar to GPS.
It covers India and areas up to about 1500 km beyond its borders.
It is operated by ISRO.
Which of the statements given above is/are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 3 only
D. 1, 2 and 3
Answer: A
Explanation:
Statement 1 is incorrect because NavIC is regional, not global. Statements 2 and 3 are correct.
Q. Atomic clocks on navigation satellites are primarily used for:
A. Measuring satellite altitude
B. Maintaining precise timing signals for positioning calculations
C. Monitoring solar radiation in space
D. Controlling satellite propulsion systems
Answer: B
Explanation:
Atomic clocks provide extremely precise time signals, which allow receivers to calculate distance from satellites and determine location.
Q. Consider the following satellite navigation systems:
GPS
Galileo
BeiDou
NavIC
Which of the above provide global navigation coverage?
A. 1, 2 and 3 only
B. 1 and 4 only
C. 2 and 3 only
D. 1, 2, 3 and 4
Answer: A
Explanation:
GPS, Galileo and BeiDou are global navigation systems, whereas NavIC is regional.