ISRO’s navigation satellite IRNSS-1I, on board PSLV-C41, lifts off at the Satish Dawan Space Centre in Sriharikota in Andhra Pradesh.(AFP)
ISRO’s navigation satellite IRNSS-1I, on board PSLV-C41, lifts off at the Satish Dawan Space Centre in Sriharikota in Andhra Pradesh.(AFP)

ISRO successfully launches IRNSS-1I navigation satellite

IRNSS-1I is expected to replace IRNSS-1A, the first of the seven navigation satellites, that was rendered ineffective after its three rubidium atomic clocks failed.
Malavika Vyawahare, Hindustan Times, New Delhi | By Malavika Vyawahare
UPDATED ON APR 12, 2018 10:44 PM IST

The Indian Space Research Organisation (ISRO) successfully launched the IRNSS 1I navigation satellite from the Satish Dhawan Space Centre at Sriharikota, Andhra Pradesh, on the 43rd flight of the Polar Satellite Launch Vehicle (PSLV), early on Thursday morning.

The IRNSS 1I mission is critical for the space agency as it is ISRO’s second attempt to replace the IRNSS 1A satellite, after the failure of the IRNSS 1H mission in August ISRO’s last mission is in jeopardy as the space agency lost contact with GSAT 6A a few days after launch on March 31.

Prime Minister Narendra Modi congratulated ISRO scientists for the successful launch and said it will benefit the common man of the country. “Congratulations to our scientists on the successful launch of navigation satellite IRNSS-1I by PSLV. This success will bring benefits of our space programme to the common man. Proud of team @isro!,” the Prime Minister tweeted.

The Indian Regional Navigation Satellite System (IRNSS) is a constellation of seven satellites that provides indigenously developed regional GPS services called NavIC. The rubidium-based atomic clocks onboard the IRNSS 1 A failed and it was no longer useful for providing navigation services.

“This NavIC constellation is really going to create history and make innovative applications to the entire community in the ocean-based services especially for the underserved and unserved,” K Sivan, chairman of ISRO, said.

“Very recently using the NavIC applications we have created an app that will be released very soon. I request industry and institutions to come forward to take these applications to the user community.”

The space agency has faced flak from the Comptroller and Auditor General for NavIC still not being fully operational, after more than 10 years of its launch and had cost Rs 1,284 crore.

The 7 IRNSS satellites were launched between 2013 and 2016, with IRNSS 1A being the first. By mid-2016 problems surfaced with atomic clocks on board the satellite. “For a foolproof navigation system that covers the entire country all 7 satellites have to be functional,” Ashish Agarwal, a scientist at National Physical Laboratory, said.

The clocks were manufactured by Spectracom, which is part of the Orolia Group, that is headquartered in the US. The group also supplied clocks for the IRNSS 1I. Though the technology for rubidium clocks has been developed in India, it isn’t proven yet.

The IRNSS 1I was placed in a sub-geosynchronous transfer orbit by the PSLV following which orbit raising manoeuvres that rely on the satellite’s own propulsion system will place it in the targeted geosynchronous orbit at 36,000 km height.

Though the space agency has suffered two setbacks in less than nine months, the launch of two satellites in two weeks comes as a big boost for ISRO. There are nine more launches this year.

“We have lot more challenges for the ISRO community. I am sure they will rise to the occasion,” Sivan said.

Over the next few days, the progress of the IRNSS 1I mission will be closely watched. In the case of GSAT 6A, the orbit raising manoeuvres could not be completed because of the snapped communication link which meant that ISRO could not guide it to its targeted orbit.

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