India Launches Sixth Navigation Satellite In Copy-Book Style
Till date, India has launched six regional navigational satellites (IRNSS-1A, 1B, 1C, ID, 1E and 1F) as part of a constellation of seven satellites to provide accurate position information service to users across the country and the region, extending up to an area of 1,500 km.
Though the full system comprises nine satellites -- seven in orbit and two on the ground as stand-by, the navigation services could be made operational with four satellites, ISRO officials had said earlier.
Each satellite costs about 
150 crore and the PSLV-XL version rocket costs about 130 crore. The seven rockets would entail an outlay of about 910 crore.
The entire IRNSS constellation of seven satellites is planned to be completed in 2016 itself.
The first satellite IRNSS-1A was launched in July 2013, the second IRNSS-1B in April 2014, the third on October 2014, the fourth in March 2015, and the fifth in January this year.
While the sixth satellite went up on Thursday, the seventh - IRNSS-1G - is expected to be launched in the second half of 2016.
Once the regional navigation system is in place, India need not be dependent on other platforms.
According to ISRO, even with the operationalisation of five IRNSS satellites, the proof of concept of an independent regional navigation satellite system over India has been demonstrated for the targeted position accuracy of better than 20 metres over 24 hours of the day.
The operationalisation of the sixth satellite, a better position accuracy will be provided, ISRO said.
While ISRO is silent on the navigation systems strategic application, it is clear that IRNSS will be used for defence purposes as well. Indian space agency officials said IRNSS system is unique as it consists of only seven satellites while other systems in the world have more than 20 satellites.
However, while other systems are global, Indian system is regional in nature.
At 4.01 p.m. the PSLV rocket standing 44.4 metres tall and weighing 320 tonnes tore into the evening sky with a fierce orange flames at its tail. The rocket took off with a delay of one minute to avoid collision with space debris.
Gathering speed every second, the rocked raced towards space amidst the cheers of the ISRO officials and the media team assembled at the rocket port here.
At the rocket mission control room, Indian space scientists at ISRO were glued to their computer screens watching the rocket escaping the earth's gravitational pull.
Just over 20 minutes into the flight, the PSLV rocket ejected its sole passenger IRNSS-1F at an altitude of 488.9 km.
Soon after the ejection into the orbit, the satellite's solar panels were deployed.
The satellite's control was taken over by the Mission Control Facility (MCF) at Hassan in Karnataka.
The MCF will manage the satellite's orbit raising operations and firing the on-board motors till it is placed in its slotted orbit.
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.
While GPS and Glonass are fully functional global systems, the Chinese and the Japanese systems are offering regional coverage and Europe's Galileo is yet to be operational.
The IRNSS will provide two types of services -- standard positioning service and restricted service. The former is provided to all users and the latter is an encrypted service for authorised users.
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