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ISRO’s new NavIC satellite

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June 06, 2023

Why in news?

The Indian Space Research Organisation (ISRO) launched the first of the second-generation satellites for its navigation constellation successfully.

What is NavIC?

  • NavIC (Navigation with Indian Constellation) is a regional navigation satellite system of India.
  • NavIC is erstwhile known as the Indian Regional Navigation Satellite System (IRNSS).
  • NavIC is designed with a constellation of 7 satellites, all launched by PSLV rockets.
  • Three satellites of the constellation are placed in geostationary orbit and the other 4 satellites are placed in inclined geosynchronous orbit.
  • NavIC offers two services: Standard Position Service (SPS) for civilian users and Restricted Service (RS) for strategic users.
  • NavIC satellites will broadcast SPS signals in L1, L5 and S bands after the addition of NVS-01.
  • RS signals will be broadcasted in L5 and S bands.

What are the current issues with IRNSS constellation?

  • Atomic clock - Satellite-based positioning system determines the location of objects by using the atomic clocks on board.    
  • The atomic clocks accurately measures the time it takes for a signal to travel to and back from it.
  • In 2018, ISRO started the launch of the replacement satellites after their onboard atomic clock failed and it stopped providing accurate location data.
  • Mission Life - IRNSS-1A which was launched into orbit in 2013, is almost defunct.
  • All the 3 oldest satellites in the constellation are close to the end of their 10-year mission lives.
  • At least three new satellites must be put into orbit to keep the seven-satellite constellation fully functional.
  • Signal Band - The L1 frequency is among the most commonly used in the Global Positioning System (GPS).
  • Earlier IRNSS used only L5 and S frequencies, this limits the interoperability with other global navigation satellite system (GNSS).

What is second generation satellites?

  • They are replacement satellite for the Indian Regional Navigation Satellite System.
  • The second generation satellites will replace satellites located at a geosynchronous orbit with additional features.
  • NVS series of satellites will sustain and augment the NavIC with enhanced features.
  • NVS-01 - It is the first of the second-generation satellites envisaged for NavIC services.
  • NVS-01 was launched by a Geosynchronous Satellite Launch Vehicle (GSLV) rocket.
  • It is the heaviest satellite in the constellation weighing 2,232 kg.

What’s new in the second-generation NavIC satellite?

  • Mission Life - The second-generation satellites will also have a longer mission life of more than 12 years.
  • The existing satellites have a mission life of 10 years.
  • New band (L1) - The NVS series incorporates L1 band signals additionally to widen the services.
  • The existing satellites provide L5 and S frequency signals.
  • L1 signals increases the interoperability with other satellite-based global navigation systems.
  • It will increase the use of NavIC in wearable devices and personal trackers that use low-power, single-frequency chips.
  • Atomic clock - For the first time, an indigenous atomic clock will be flown in NVS-01.
  • The satellite will have a Rubidium atomic clock onboard, indigenously developed by Space Application Centre-Ahmedabad.

What practical purpose does the NavIC constellation serve for users?

  • After the development of the user receivers, NavIC is used for practical public applications.
  • NavIC is in use for projects like public vehicle safety, power grid synchronisation, real-time train information systems, and fishermen’s safety.
  • Initiatives such as common alert protocol based emergency warning and unmanned aerial vehicles are in the process of adopting NavIC system.
  • The Ministry of Electronics and IT urging smartphone companies to make their handsets NavIC compatible.

What is the advantage of having a regional navigation system?

  • There are four global satellite-based navigation systems
    • The American GPS
    • The Russian GLONASS
    • The European Galileo
    • The Chinese Beidou
  • Japan has a 4-satellite system that can augment GPS signals over the country, similar to India’s GAGAN.
  • India is the only country that has a regional satellite-based navigation system.
  • Accuracy - GPS signals are accurate up to around 20 metres whereas NavIC open signals will be accurate up to 5 metres and restricted signals will be even more accurate when fully operational.
  • Coverage - NavIC provides coverage over the Indian landmass and up to a radius of 1,500 km around it.
  • Consistency - NavIC uses satellites in high geo-stationery orbit which enables the satellite to look over the same region on Earth always.
  • Penetration - NavIC signals come to India at a 90-degree angle, making it easier for them to reach devices located even in congested areas, dense forests, or mountains.

References

  1. IE - ISRO’s new NavIC satellite launches successfully
  2. ISRO - Navigation with Indian Constellation (NavIC)
  3. ISRO - GSLV-F12/NVS-01 Mission
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