India has realised its long-cherished dream of owning an indigenous navigation satellite system, NavIC (navigation with Indian constellation); with the successful launch of IRNSS-1I (to be read as ‘one eye’, I is the letter). A Polar Satellite Launch Vehicle(PSLV-C41) carrying the navigation satellite blasted off from the Satish Dhawan Space Centre at Sriharikota, in the southern coastal state of Andhra Pradesh.
The PSLV rocket placed the satellite in its designated geosynchronous orbit—just 19 minutes after it soared into the sky. The satellite is working well.
ISRO Chairman K Sivan congratulated the scientists and engineers involved in the mission. He said, “I am grateful to the entire ISRO family for having worked this hard and making IRNSS-1I a success.”
IRNSS-1Iis expected to replace IRNSS-1A, the first of the seven navigation satellites that was rendered ineffective in January 2017 after its three rubidium atomic clocks failed. The seven satellites are part of the NavIC (Navigation with Indian Constellation). TheIRNSS-1I is the last satellite in this constellation.
ISRO launched the first seven navigation satellites–IRNSS-1A to 1G—between July 2013 and April 2016. Both IRNSS-1I and IRNSS-1H are planned as backups. They became necessary after all the three imported rubidium atomic clocks on INRSS-1A failed in orbit. All the seven satellites are required for accurate, 24-hour information from the fleet.
Hence, both the IRNSS-1I and IRNSS-1H satellite were fitted with corrected atomic clocks. They were built by a consortium of six Indian companies which were involved in their assembly, integration and testing in Bengaluru.
The IRNSS-1I mission was launched two weeks after the communication satellite GSAT-6A that was put into space on March 29, lost contact with ground. ISRO has since located the GSAT-6A and is trying to establish communication.
Dubbed as India’s own GPS (Global Positioning System), the navigation satellites are expected to give precise information about position, navigation and time related to objects or people.
Dr Sivan said, the NavIC constellation is going to create history and make innovative applications for the entire community of position-based services, especially the underserved and un-served.
The navigation satellites will have both limited military/security and civilian applications to aid security and disaster management and fleet monitoring on land, air and sea. The IRNSS-1I will broadcast highly-accurate timing signals that a receiver can use to triangulate its location. The constellation will also provide positional information in a space covering India and its surroundings, which could be used by ground receivers to determine the position and time accurately.
The IRNSS-1I is expected to achieve its designated roles in about a month, after routine orbit manoeuvres and tests. It has been built to perform tasks for ten years in space.
The launch is the culmination of 17 years of hard work by Indian space scientists. As in the previous launches of the IRNSS satellites, PSLV-C41 has also used ‘XL’ version of PSLV equipped with six strap-ons–with each carrying 12 tonnes of propellant.
ISRO adopted a new technology called friction stir welding, which will improve the productivity and enhance the payload capability of the vehicle. This time, the participation by the industry was enhanced.
ISRO is now working on advanced navigation satellites, which will constitute the phase two of IRNSS programme. Significantly, instead of imported clocks, navigation satellites will have rubidium atomic clocks developed by the Space Applications Centre in Ahmedabad.
The next eight months are going to be challenging for ISRO, which plans to put nine missions into space. The prestigious Chandrayaan-2 landing and rover mission to the moon is slated for late 2018.
Another important project is the second confirmatory launch of GSLV-MkIII heavy-lift rocket. It will carry the three-tonne-plus GSAT-29 communication satellite to space. The success of this mission will regularise the much-needed MkIII rocket to lift ISRO’s four-tonne communication satellites to orbit. This may put an end to hiring foreign launchers for this size of satellites in the near future. Besides, ISRO is readying the very heavy 5.7-tonne GSAT-11 high-throughput or broadband satellite, which will be launched on a European rocket. The space agency is also lining up a number of PSLV missions with Earth observation satellites.
The next phase of global competition is likely to be space technology. India’s growing capability and expertise will give the country an added advantage in the development race.
Script: K V Venkatasubramanian, Science Journalist