ISRO’s NavIC navigation system disrupted due to atomic clock failure

The Indian Space Research Organisation (ISRO) announced that the atomic clock installed on the satellite (IRNSS)-1F of India’s regional navigation system has stopped functioning.

This has come amid other technical setbacks in India’s navigation constellation, including the failure of the NVS-02 satellite to reach its final orbit, raising concerns about the reliability of NavIC (Navigation with Indian Constellation).

After the failure of the atomic clock of IRNSS-1F, currently only four satellites are capable of providing real data: IRNSS-1B, 1C, 1I and the new-generation NVS-01.

ISRO developed indigenous rubidium atomic clocks to reduce dependence on imported frequency standards. These clocks will power the next generation of satellites (NVS series).

Qualcomm chipsets started supporting NavIC signals in the year 2020. In 2019, the United States recognized NavIC as an allied navigation system under the National Defense Authorization Act, 2020.

About NavIC

The Indian Regional Navigation Satellite System (IRNSS), operationally known as Navigation with Indian Constellation (NavIC), is India’s indigenous satellite navigation system.

It was designed to provide accurate position information to users in India and up to 1500 km beyond its borders, which constitutes the primary service area.

Additionally, an extended service area covers the region bounded between the primary area and a rectangle between 30° South to 50° North latitude and 30° East to 130° East longitude. This project was initiated to ensure strategic autonomy in navigation services.

During the Kargil conflict of 1999, the United States denied India access to GPS data, exposing the risks of relying on foreign systems. To address this vulnerability, India approved the NavIC project in the year 2006.

Unlike GPS, NavIC uses dual frequencies (L and S bands), allowing better correction of atmospheric errors and potentially higher accuracy.

It performs better than global systems in challenging terrains such as valleys, forests, and urban areas where GPS signals may be weak.

Major satellites related to NavIC

The first generation of NavIC satellites includes the IRNSS-1 series, launched between 2013 and 2018. Key satellites include IRNSS-1A, 1B, 1C, 1D, 1E, 1F, 1G and the replacement satellite IRNSS-1I.

IRNSS-1H (2017), which was launched to replace IRNSS-1A, failed to reach orbit due to heat shield separation failure.

After the failure of the IRNSS-1H mission in 2017, IRNSS-1I was launched in 2018 as a replacement.

The NVS series represents the second generation of NavIC satellites. It includes NVS-01 and NVS-02.

NVS-01 (2023) is operational and includes an indigenously developed rubidium (atomic) clock and L1 band signals.

NVS-02 (2025) faced issues in reaching its final operational orbit due to an onboard technical problem.

The mission life of new satellites is 12 years, which is an improvement over the previous generation’s 10-year lifespan.

Navigation systems of other countries

Global Navigation Satellite System (GNSS)

United States: Global Positioning System (GPS)

Russia: Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS)

European Union: Galileo

China: BeiDou

Japan: Quasi-Zenith Satellite System (QZSS)