India's indigenous navigation satellite system just suffered a major setback
What's the story
India's indigenous navigation satellite system, the Navigation with Indian Constellation (NavIC), has suffered a major setback. One of its four operational satellites, IRNSS 1-F, has failed after its last functional atomic clock malfunctioned. The development was confirmed by officials from the Indian Space Research Organisation (ISRO). The satellite had been operating with only one of its three onboard atomic clocks.
Satellite status
IRNSS 1-F will continue to function in orbit
ISRO clarified that despite the failure of its atomic clock, the IRNSS 1-F satellite will continue to function in orbit for various societal applications. However, it will only provide one-way broadcast messaging services. The satellite was launched on March 10, 2016, and had completed its design mission life of 10 years on March 10 this year.
Service disruption
Only 3 satellites operational for NavIC system
The NavIC system requires at least four indigenous navigation satellites to be fully operational for it to provide navigation services. This includes services for the public and government agencies such as railways and military. With the failure of IRNSS 1-F, only three satellites are currently functional for Positioning, Navigation, and Timing (PNT) services: IRNSS 1-B, IRNSS 1-L, and IRNSS 1-J (NVS-01).
Historical issues
Other satellites also experienced atomic clock failures
The failure of the IRNSS 1-F satellite's atomic clock is not an isolated incident. Five other satellites launched for the NavIC system have also experienced atomic clock failures: IRNSS-1A, IRNSS-1C, IRNSS-1D, IRNSS-1E, and IRNSS-1G. These problems have mostly been linked to defective imported atomic clocks in the early years and orbital issues on a few recent occasions.
Official statement
Government on satellite status last year
In a parliamentary reply last year, the government had said that only four of the 11 satellites launched for the NavIC system were operational for PNT services. The rest were being used on a sub-optimal basis. "As of now, 11 satellites have been put in orbit. Some of them are not functioning," Minister of State Jitendra Singh had said at the time.