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UPSC 2018 GS-I · 10 marks · 150 words

Why is the Indian Regional Navigational Satellite System (IRNSS) needed? How does it help in navigation?

What “Explain” demands

set out how or why something works, with the mechanism made explicit.

The characteristic failure: stating that it works without showing how.

What a top answer must contain

These are the checkable specifics from the marking standard for this question — the actual case, committee, datum or thinker, not an instruction to “give examples”.

  • Strategic need: the 1999 Kargil episode when GPS access was denied — sovereign positioning capability as the origin
  • Constellation: seven satellites, NavIC, coverage of India plus 1,500 km around it
  • Services: Standard Positioning Service for civilians and Restricted Service for authorised users, ~20 m accuracy over the primary zone
  • Applications: terrestrial and marine navigation, disaster management, fleet tracking, fishermen alerts, mobile-handset mandate
  • Comparison: regional system versus global GPS, GLONASS, Galileo, BeiDou

The band thresholds and the pre-scored sample answers behind this standard stay private — they are the calibration your copy is placed against.

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