Context: Recently, the Indian Space Research Organisation (ISRO) launched the first of the second-generation satellites for its navigation constellation successfully from Sriharikota.

How second-generation NavIC satellite is different?

• The second-generation NavIC satellite was launched by a Geosynchronous Satellite Launch Vehicle (GSLV) rocket.

• Whereas, the Indian Regional Navigation Satellite System (IRNSS) constellation was launched by a lighter Polar Satellite Launch Vehicle (PSLV), ISRO’s workhorse launch rocket.

• The second-generation NavIC satellite is the heaviest in the constellation with a 2,232 kg weight.

• Combined mass of the existing IRNSS constellation is around 1,425 kg at liftoff.

Which satellites were launched before the second-generation NavIC satellite is different?

• In April 2018, IRNSS-1I was launched to replace an older, partially defunct satellite in the constellation.

• IRNSS-1I was ISRO’s ninth satellite for the NavIC constellation but is considered to be the eighth because the IRNSS-1H launched eight months earlier in August 2017 was lost after the heat shield of the payload failed to open on time.

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

Atomic Clock

• It will have a Rubidium atomic clock onboard, developed by India.

• The clock is developed by Space Application Centre-Ahmedabad and is an important technology that only a handful of countries possess.

L1 signals for better use in wearable devices

• The second-generation satellites will also send signals in L1, a third frequency.

• Existing satellites used to send signals in L5 and S frequency.

• The L1 frequency is among the most commonly used in the Global Positioning System (GPS).

• The L1 frequency will increase the use of the regional navigation system in wearable devices and personal trackers that use low-power, single-frequency chips.

Longer mission life

• It will also have a longer mission life of more than 12 years.

• The existing satellites have a mission life of 10 years.

What are the concerns related to IRNSS?

Failure of Atomic Clocks

• Due to onboard atomic clocks failure several existing satellites stopped providing location data.

• Failure of clocks means the satellites are no longer able to provide accurate locations because a satellite-based positioning system determines the location of objects by accurately measuring the time it takes for a signal to travel to and back from it using the atomic clocks on board.

• As of now only four IRNSS satellites can provide location services.

• The other satellites can only be used for providing disaster warnings or potential fishing zone messages for fishermen.

Age of the satellites

• IRNSS-1A was launched into orbit on July 1, 2013, and the 1B and 1C satellites were launched in the following year.

• IRNSS-1A is almost defunct, the failed 1H mission of 2018 was intended to replace this satellite.

• All three 1A, 1B and 1C 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.

What practical purpose does the NAvIC constellation serve for users?

• NavIC is in use for projects like public vehicle safety, power grid synchronisation, real-time train information systems, and fishermen’s safety.

• Other upcoming initiatives such as common alert protocol-based emergency warning, time dissemination, geodetic network, and unmanned aerial vehicles are in the process of adopting the NavIC system.

• The Ministry of Electronics and IT is in talks with smartphone companies to urge them to make their handsets NavIC compatible.

How many countries have a regional navigation system?

• India is the only country that has a regional satellite-based navigation system.

• There are four global satellite-based navigation systems: American GPS, Russian GLONASS, European Galileo, and Chinese Beidou.

• Japan has a four-satellite system that can augment GPS signals over the country, similar to India’s GAGAN (GPS Aided GEO Augmented Navigation).

What are the advantages of having a regional navigation system?

• NavIC open signals will be accurate up to 5 metres and restricted signals will be even more accurate.

• GPS signals by contrast are accurate up to around 20 metres.

• NavIC provides coverage of the Indian landmass and up to a radius of 1,500 km around it.

• NavIC signals will likely be available in even hard-to-reach areas.

• NavIC uses satellites in high geo-stationery orbit, the satellites move at a constant speed relative to Earth, so they are always looking over the same region on Earth.

• 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.

• GPS signals are received over India at an angle.