Countdown progressing for ISRO's navigation satellite launch

The countdown for the launch of navigation satellite 'IRNSS-1H' from Sriharikota later today, to augment the existing seven satellites of the NavIC constellation, is progressing well, ISRO sources said.
The 29-hour countdown began yesterday at 2pm and scientists are currently involved in filling up the propellants, they said, adding that the countdown is progressing well.
The Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) had on August 29 cleared the countdown.
The launch vehicle PSLV-C39 will use the 'XL' variant, of PSLV equipped with six strap-ons, each carrying 12 tons of propellant.
The 44.4 metre tall PSLV-C39 in its 41st flight, carrying the 1,425 kg satellite, is scheduled for a lift-off at 1900hrs today from the second launch pad at the spaceport of Sriharikota, about 110km from here.

The spacecraft was built andtested by ISRO along with a consortium of six small and mediumindustries.

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 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 system that offer services like terrestrial and marine navigation, disaster management, vehicle tracking and fleet management, navigation aide for hikers and travellers, visual and voice navigation for drivers, was named 'NavIC' (Navigation with Indian Constellation) by Prime Minister Narendra Modi.

ISRO had launched seven satellites - IRNSS-1G on April 28, 2016, IRNSS-1F (March 10, 2016), IRNSS-1E (January 20, 2016), IRNSS-1D (March 28, 2015), IRNSS-1C (October 16, 2014), IRNSS-1B (April 4, 2014) and IRNSS-1A on July 1, 2013.
According to ISRO officials, the total cost of all the seven satellites was Rs 1,420 crore.