Sriharikota: The Indian Space Research Organisation (ISRO) began the countdown to launch the navigation satellite IRNSS-1H from Sriharikota today.
The launch will augment the existing seven satellites of the NavIC constellation.
IRNSS-1H would be a back up navigation satellite for IRNSS-1A one of the seven satellites of the constellation, as its three rubidium atomic clocks on board had stopped functioning.
The launch vehicle PSLV-C39 rocket will carry the satellite.
The Indian Regional Navigation Satellite System (IRNSS) is an independent regional system developed by India on par with the US-based GPS, Glonass of Russia, and Galileo developed by Europe.
The 44.4 metre tall PSLV-C39 in its 41st flight, carrying the 1,425 kg satellite, was scheduled for a lift-off at 7:00pm from the second launch pad at the spaceport of Sriharikota, about 110km from Chennai.