ISRO to Launch Satellite to Replace IRNSS-1A on April 12

Saul Bowman
April 13, 2018

Indian Space Research Organisation successfully launched IRNSS-1I into Geosynchronous orbit (GSO) using the Polar Satellite Launch Vehicle C41 on Thursday morning, April 12, 2018 at 0404 (IST) from its Satish Dhawan Space Centre spaceport at Sriharikota.

The IRNSS-1I will replace the IRNSS-1A which was rendered ineffective as the onboard atomic clocks had failed.

To a question on ISRO getting its basic needs right- heavy lift rockets, heavier or higher capacity satellites instead of inter-planetary missions- Sivan said work had already started to increase the carrying capacty of the Geosynchronous Satellite Launch Vehicle (GSLV) Mk-III to 6 tonnes.

IRNSS-1I will add to the constellation of navigation satellites, which is called Indian Regional Navigation Satellite System (IRNSS). The goal of these IRNSS satellites is to create India's own navigation system which would be in the lines of US' GPS or Global Positioning System. The spacecraft's other two clocks failed over the next six months, leaving it unable to broadcast navigation data. The other IRNSS payload built and launched by India failed to enter the navigation network when it was stranded on its rocket during a PSLV flight in August. The four stage/engine PSLV-XL stands 44.4 metres tall and weighs 321 ton at the lift-off stage.

Explaining the reason for choosing this time slot, former Isro Satellite Centre director TK Alex said, "Different satellites have to be put in different locations".


Alpha Design Technologies, which is headquartered in Bengaluru, played an important role in the integration of IRNSS-1I satellite.

While IRNSS-1I will replace IRNSS-1A, ISRO has no intention of de-orbiting the latter. According to ISRO, NavIC is useful for fishermen to reach potential fishing areas. The fishermen can also get alert messages relating to bad weather, high waves or when they approach the global maritime boundary line.

After the satellite is pushed into its preliminary orbit, the master control facility (MCF) at Hassan, Karnataka, will guide it through three orbit-raising manoeuvres with the help of engines on-board the IRNSS-1I.

People can use these services which are provided through a software application on a smart phone. IRNSS provides two types of services, namely, Standard Positioning Services provided to all users and Restricted Services, provided to authorised users. This was a failure as the rocket's heat shield did not separate three minutes after lift-off and the satellite remained housed inside the heat shield.

IRNSS-1L is developed to function for a period of 10 years wherein the scientists will boost its orbit, maneuver it accordingly.

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