Why in the news

  • ISRO announced launch of replacement satellites before 2026 to substitute defunct satellites of NavIC (Indian GPS).

Navigation with Indian Constellation (NavIC)

  • Type: Autonomous regional satellite navigation system by ISRO.
  • First launch: 2013
  • Lifetime: 12 years.
  • Coverage
    • India + 1,500 km beyond Indian mainland (primary coverage).
    • Future expansion planned.
  • Satellites
    • Present constellation: 7 satellites (with 2 standby on ground).
    • Placement
      • 3 in Geostationary Earth Orbit (GEO).
      • 4 in Inclined Geosynchronous Orbit (IGSO).
  • Accuracy
    • Better than 10 m across Indian landmass.
    • Better than 20 m in Indian Ocean.

Global Comparison of Navigation Systems

  1. GPS (US):
    • 31 satellites, global coverage, launched in 1978.
    • Lifetime: 10 years, precision: 5 m.
  2. GLONASS (Russia):
    • 24 satellites, global coverage, launched 1982.
    • Lifetime: 10 years, precision: 5–10 m.
  3. Galileo (EU):
    • 40 satellites planned (10 active), launched 2011.
    • Lifetime: 12 years, precision: 1 m public, 1 cm military.
  4. BeiDou (China):
    • Two constellations (regional + global).
    • Full-scale global navigation system.