Three Satellites Short: Why NavIC Can Still Tell the Time but No Longer Tell You Where You Are
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Article summary
The Government informed Parliament in late July 2026 that NavIC, India's regional satellite navigation system, cannot currently provide standalone positioning services. Only three satellites remain operational for positioning, navigation and timing: IRNSS-1B, IRNSS-1I and NVS-01. A receiver needs signals from at least four satellites to fix a position, because it must solve for three spatial coordinates plus its own clock error, so three satellites are geometrically insufficient. The immediate trigger was the failure of the last atomic clock aboard IRNSS-1F in March 2026, extending a pattern of clock failures that has dogged the constellation since 2017. NavIC continues to broadcast timing signals and emergency messages, and the armed forces operate on hybrid GNSS receivers that draw on multiple constellations. ISRO has NVS-03 ready for launch, with NVS-04 and NVS-05 in advanced stages.
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Sample questions — answers revealed after test
Q1. NavIC, India's regional navigation system, is designed around a constellation of how many satellites, and covers which area?
Q2. Why must a satellite navigation receiver have signals from at least four satellites to fix its position?
Q3. Consider the following statements about the NavIC shortfall: 1. Repeated failures of onboard rubidium atomic clocks have been the principal cause of attrition in the constellation. 2. A satellite whose clocks have failed remains in orbit but is unusable for navigation. 3. Because NavIC cannot currently provide standalone positioning, Indian users and the armed forces have lost access to satellite navigation. Which of the statements given above are correct?