Context
Failure of an atomic clock on an IRNSS (NavIC) satellite has weakened India’s regional navigation capability; the Indian Space Research Organisation (ISRO) plans indigenous replacements for future satellites.
Navigation Satellite System (NavSat) — Basics
- A satellite-based system that provides Positioning, Navigation and Timing (PNT) services.
- Satellites transmit time-stamped signals; receivers determine location using trilateration.
- Key uses include aviation, maritime transport, mapping, disaster management, telecom synchronization and defence.
India’s Navigation System — NavIC (IRNSS)
- Full form: Navigation with Indian Constellation (NavIC); earlier called Indian Regional Navigation Satellite System (IRNSS).
- Coverage: India and about 1,500 km beyond its borders.
Services
Standard Positioning Service (SPS) for civilians
Restricted Service (RS) for authorised users
Orbit-wise Distribution
Geostationary Orbit (GEO)
3 satellites
IRNSS-1C
IRNSS-1F
IRNSS-1G
Inclined Geosynchronous Orbit (IGSO)
4 satellites
IRNSS-1A
IRNSS-1B
IRNSS-1D
IRNSS-1E
GEO satellites remain fixed over the equator.
IGSO satellites trace a figure-8 pattern over India for better regional coverage.
Major Global Navigation Satellite Systems (GNSS)
GPS — United States
GLONASS — Russia
Galileo — European Union
BeiDou — China
NavIC (IRNSS) — India
Atomic Clocks — Role
- Highly precise rubidium/cesium clocks onboard satellites.
- Provide exact timing signals essential for accurate positioning.
- Even nanosecond errors can cause large location inaccuracies.
- Also support telecom networks, banking systems, power grids and scientific applications.
