ISRO’s IRNSS-1G satellite launch: 5 facts about India's 'back-up' navigation system

3.The IRNSS will be providing two types of services — standard positioning service and restricted service.

The countdown for today's launch of navigation satellite 'IRNSS-1H' is all set and to be launched on board PSLV-C39, IRNSS-1H will be a 'back-up' navigation satellite for IRNSS-1A, one of the seven satellites in the constellation, as its three rubidium atomic clocks on board had stopped functioning. The satellite launch is scheduled at 19:00 Hrs from the Second Launch Pad of the Satish Dhawan Space Centre at Sriharikota in Andhra Pradesh. The launch vehicle PSLV-C39 will use the 'XL' version of PSLV equipped with six strap-ons, each carrying 12 tons of propellant. Here are five facts about India’s own IRNSS-1G:

1. The IRNSS-1G (Indian Regional Navigation Satellite System-1G) is a part of a constellation of seven satellites so that it can provide accurate position information service to users across the country.

2.The IRNSS is similar to the global positioning system (GPS) of the US (24 satellites), Glonass of Russia, and Galileo of Europe as well as China’s Beidou.

4. Till date, 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.

5. Each satellite costs about Rs.150 crore while the PSLV-XL version rocket costs about Rs.130 crore. The seven rockets would entail an outlay of about Rs.910 crore. The first satellite, IRNSS-1A, was launched in July 2013, the second in April 2014, the third on October 2014, the fourth in March 2015, and the fifth and sixth on January 20 and March 10 this year. Once the regional navigation system is in place, India does not need to depend upon other platforms.