UPSC Mains 2018 GS Paper 1 Q4: model answer
Why is Indian Regional Navigational Satellite System (IRNSS) needed? How does it help in navigation?
What the question wants
Explain why India needs its own regional navigation satellite system and how it works for navigation.
How to structure it
Two parts: Why needed and How it helps.
- What it is
- Why India needs it
- How it works
- Uses
How to think it through
During the 1999 Kargil conflict India reportedly could not get GPS data for the region. That story explains the 'why'. The 'how' is simple geometry: know your distance from at least four satellites and you know where you are.
Model answer
During the Kargil conflict of 1999, India is reported to have been denied GPS data for the region. That experience drove ISRO to build its own system, the Indian Regional Navigation Satellite System (IRNSS), now called NavIC.
Why it is needed
- Strategic autonomy: no dependence on foreign systems (GPS, GLONASS) that can be switched off in a crisis.
- Accuracy over India: better than 20 m for civilian users, and finer encrypted service for the military.
- Coverage: India and up to 1,500 km around it, covering the Indian Ocean region.
How it helps navigation
- Seven satellites (three geostationary, four geosynchronous) are always visible over India.
- A receiver measures signal travel time from several satellites to fix position, speed and time.
- Uses two frequency bands (L5 and S), reducing errors from the ionosphere.
- Ground stations and atomic clocks keep timing precise; new NVS satellites add the L1 band for phones.
Uses
- Fishermen's alerts, aircraft and ship navigation, disaster management, vehicle tracking (mandatory for public vehicles), timing for banks and power grids, mobile phones.
Draw: Indian map with seven satellite positions around it.
Keywords, cases and data to drop in
NavIC, seven satellites, L5 and S band, Kargil 1999, SPS and RS services, NVS-01 (2023).
Where most answers lose marks
- Confusing NavIC with GAGAN, which only augments GPS.
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Question text as printed in the official UPSC Civil Services (Main) question paper. The model answer is original Battle IAS work; use it to learn structure, not to memorise.
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