India’s indigenous navigation satellite system—Navigation with Indian Constellation (NavIC)—has suffered a major setback with one of its four operational satellites reporting a failure “at the end of 10 years since its launch”, according to Indian Space Research Organisation (Isro) officials.
The Indian Regional Navigation Satellite System’s IRNSS 1-F, launched on March 10, 2016, failed after its last functional atomic clock malfunctioned, space department sources indicated. The satellite had been operating with only one of its three onboard atomic clocks.
At least four indigenous navigation satellites must be fully operational for the NavIC system to provide navigation services to the public and government agencies such as railways and the military.
Senior ISRO officials associated with the NavIC satellites and the space programme did not respond to queries on the failure of the IRNSS 1F satellite. Isro chairman Dr V Narayanan did not speak on the issue but referred to an official statement posted on its website.
“On 13th March 2026, the procured on-board atomic clock stopped functioning. However, the satellite will continue to function in-orbit for various societal applications to provide one way broadcast messaging services,” Isro said in an official statement on Friday night.
“IRNSS-1F satellite launched in March 2016 has completed its design mission life of 10 years on 10th March 2026,” the statement posted on the Isro website said.
Although Isro has launched 11 satellites since July 2013 for the nearly Rs 2,250 crore NavIC system, six satellites have failed primarily due to defective imported atomic clocks in the initial years, and on a few recent occasions, due to orbital issues.
Story continues below this ad
Last year, in a reply in Parliament, the Union government had reported that only four of 11 satellites launched for the NavIC system were operational for positioning, navigation, and timing services, with the others being used on a sub-optimal basis.
“As of now, 11 satellites have been put in orbit. Some of them are not functioning. At present, four satellites are providing Position, Navigation and Timing (PNT) services, four satellites are being used for one way message broadcast, one satellite got decommissioned after its end-of-life service. Two satellites could not reach the intended orbit,” Minister of State for the PMO, Jitendra Singh, said in a reply in the Lok Sabha on July 23, 2025.
With the reported failure of the IRNSS 1-F, the functional NavIC satellites for PNT services at present are only the IRNSS 1-B, IRNSS 1-L, and IRNSS 1-J (NVS-01). With the reported failure of all atomic clocks on the IRNSS 1-F, a total of six of 11 Indian satellites meant for the NavIC system have failed due to the atomic clocks.
“Location services provided by the NavIC system in India are going to be affected,” space department sources said.
Story continues below this ad
Last year, in the July 23 reply in Parliament, the Union government had stated that “around 12,000 trains are targeted for tracking in real-time using NavIC and other GNSS constellations” and that “around 8,700 trains are already equipped with NavIC along with other GNSS constellations”.
ALSO READ | Story of NavIC: crucial indigenous SatNav system, a few hurdles in development path
Previous failures of NavIC satellites
Apart from the latest incident, five satellites launched for the NavIC system have experienced atomic clock failures: IRNSS-1A (launched on July 1, 2013), IRNSS-1C (October 16, 2014), IRNSS-1D (March 28, 2015), IRNSS-1E (January 20, 2016), and IRNSS-1G (April 28, 2016).
Accurate time keeping lies at the heart of navigation systems since the determination of a person’s position on earth is subject to the accurate calculation of delays in signal transmission from satellite to earth.
Story continues below this ad
Small errors in atomic clocks on satellites can skew position data by several hundred kilometres. Isro incidentally started work on the IRNSS program in 1999 after the Kargil war, where Indian defence forces could not use US-owned GPS systems to provide locational aid to its soldiers in the conflict zone.
Isro admitted in July 2016 that IRNSS 1A had developed problems due to malfunctioning atomic clocks and indicated that replacement satellites would be launched with modified clocks.
The atomic clocks in the IRNSS satellites launched after July 2016 (IRNSS 1H, 1-I) have carried modified versions of the original clocks provided by an European supplier under a $ 4 million euro deal for an estimated 45 clocks (three clocks are present on each satellite).
The IRNSS 1-J, which is currently operational, and the IRNSS 1-K, which reported an engine failure last year, are also called NVS-01 and NVS-02 satellites on account of being a second generation of IRNSS navigation satellites that are equipped with a mix of indigenous and foreign atomic clocks.
Story continues below this ad
Though a seven-satellite constellation is considered ideal for the NavIC system, four fully operational satellites are also considered to be sufficient to provide navigation services. “To provide a solution for position navigation and timing, only four satellites are needed—for timing, only one satellite is sufficient, and for position navigation, four satellites are sufficient. So we do have an indigenous solution through the IRNSS constellation at present,” the spacecraft director for the NVS-02 mission, Kartik A, had said on January 29, 2025, soon after the launch of the IRNSS 1-K (NVS-02), which did not achieve an optimum orbit location.
Satellites failing to reach optimum orbits
Two satellites—the IRNSS 1-H launched on August 31, 2017, and the IRNSS 1-K (NVS-02) launched on January 29, 2025—have had problems on account of not reaching their optimum orbits after launch.
On February 25, 2026, nearly a year after the failure of the IRNSS 1-K satellite orbit manoeuvres, Isro released a public statement on the findings of a failure analysis exercise. “On separation of the satellite from the launch vehicle, a series of autonomous activities on the satellite were carried out including the solar panel deployment and stabilizing the orientation for power generation. However, the orbit raising operations from the elliptical to circular orbit could not be carried out,” the statement said.
“The apex committee after thorough analysis of the simulation data concluded that the prime reason for the observation was found to be the drive signal not reaching the pyro valve of the oxidizer line of the engine meant for orbit raising. The committee concluded that the most likely cause for the observation is the disengagement of at least one contact (in each of the main and redundant paths) of the connector,” the statement added.
Story continues below this ad
Isro has also suffered two successive launch failures in the 2025-26 period for its workhorse PSLV rocket, resulting in an overall stalling of the launch pipeline for space programmes, including the NavIC satellite programme.
“The PSLV-C62 mission encountered an anomaly during the end of the PS3 stage. A detailed analysis has been initiated,” Isro said about the PSLV C62 launch failure on January 12, 2026. “A national level expert committee constituted is reviewing the reason for anomaly in PSLV Vehicle,” Isro said in another statement on February 25, 2026.
The Union minister of state for space had stated in Parliament in July 2025 that a new generation NavIC satellite “NVS-03 is planned to be launched by end of 2025” and “subsequently, with a gap of six months, NVS-04 & NVS-05 are planned to be launched”. But these timelines have not been realised after the launch failures for the PSLV C61 on May 18, 2025, and the PSLC C62 launch on January 12, 2026.
Isro plans to launch three second-generation NavIC satellites—NVS-03/04/05—in the future “to augment NavIC base layer constellation with enhanced features for ensuring continuity of services”.
