Topic of the Day – IRNSS-1I

UPSC Exam Preparation: Topic of the Day – IRNSS-1I


  • There are currently seven Indian Regional Navigation Satellite System (IRNSS) satellites (1A to 1G) in orbit.
    • A, B, F, G are placed in a geosynchronous orbit, which means they seem to be at a fixed location above the Earth and they orbit along with the Earth.
    • The remaining three C, D, E, are located in geostationary orbit-they seem to be at a fixed location above the Earth along the equator and orbit along with the Earth.
  • The launch of IRNSS-1I will be the ninth navigational satellite launch under the project which has seen seven successful launches and one unsuccessful launch.



  • ISRO is attempting to launch one of the backup satellites to replace NavIC navigation satellite constellation’s IRNSS-1A whose three rubidium clocks failed
  • PSLV in 43rd flight will lift off IRNSS-1I which weighs 1425 kg. It will replace IRNSS-1A and join the constellation of seven satellites.
  • It will have L5 and S-band navigation payload with rubidium atomic clocks.
  • It will be placed in a sub-geosynchronous transfer orbit and at its closest point will be 284 km above the Earth and at its farthest will be 20,650 km above the Earth.
  • Like all other IRNSS satellites, IRNSS-1I will also carry two payloads – navigation payload and ranging payload –
    • the former to transmit signals for determining position, velocity and time and
    • The latter for determining the frequency range of the satellite.


Previous attempts at replacement

  • It is ISRO’S second attempt at launching a replacement satellite.
  • The past mission in August 2017 where a PSLV carried IRNSS-1H failed after the heat shield covering the satellite failed to separate.
  • Except for IRNSS-1H, all the launches have been successful.



  • IRNSS will assist in terrestrial, aerial and marine navigation, disaster management, vehicle tracking and fleet management, integration with mobile phones, precise timing, mapping and geodetic data capture, a terrestrial navigation aid for hikers and travellers, visual and voice navigation for drivers and riders
  • Navigation satellite signal receivers which will give positioning and weather alerts to fishermen in deep sea and more such devices will be fitted in boats in Tamil Nadu and Kerala
  • This will help in sending alerts to fishermen vital information at times of cyclones



  • There are three components in the satellites’ receiver – a Bluetooth module, a microcontroller and a chipset. The receiver, developed by ISRO’s Space Applications Centre, Ahmedabad, is also being improved to save power in both mobile and the device.


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