GSAT-8 takes to the skies

India's GSAT-8 satellite has been lofted into space aboard an Ariane 5 rocket that lifted off from the European launch facility in French Guiana in equatorial South America. It is the 20th satellite designed and built indigenously by the Indian Space Research Organisation (ISRO) to meet this country's requirements for space capacity in communications and broadcasting. The 3,100-kg spacecraft's 24 transponders will relay signals in radio frequencies known as the Ku-band. These transponders will be used for Direct-To-Home television broadcasts as well as to support communications using small satellite dishes known as Very Small Aperture Terminals (VSATs). Other Indian communication satellites that are currently operational have about 150 transponders working in various frequency bands. That capacity needs to be augmented, given that a power glitch on the INSAT-4B knocked out half its transponders last July. Two satellites, GSAT-4 and GSAT-5P, were lost in consecutive failures of the Geosynchronous Satellite Launch Vehicle (GSLV) last year. Besides, the INSAT-2E, launched 12 years ago, is nearing the end of its life. ISRO plans to launch the GSAT-12, weighing 1,400 kg, on the Polar Satellite Launch Vehicle this July. The GSAT-10, with 36 transponders and weighing 3,400 kg, is to be put into orbit by another Ariane 5 rocket next year. Another communication satellite will go up when the GSLV is flown again, which is expected to take place in the first quarter of 2012.

The GSAT-8 is also carrying a payload that will broadcast data to increase the accuracy and ensure the integrity of navigation based on signals from orbiting satellites of the U.S. Global Positioning System (GPS) and the Russian Global Navigation Satellite System (GLONASS). The resulting improvement in accuracy and reliability will allow aircraft, equipped with suitable receivers, to make precision approaches for landing at all runways in the country. Aircraft will also be able to fly more direct routes to their destination, saving time and fuel. Such space-based augmentation systems have begun functioning in the U.S., Europe, and Japan. Ground stations for the Indian system, known as GAGAN (GPS Aided GEO Augmented Navigation), a joint effort by ISRO and the Airports Authority of India, have been put in place. After the GSAT-8's GAGAN payload becomes operational, further steps for testing the system as a whole and securing the necessary certification can start. All of India's remote sensing satellites are now launched domestically. This should be achieved in the case of communication satellites too. For that, the GSLV must be made as reliable as the PSLV and the next generation GSLV Mark-III got ready as soon as possible.