There are seven of them wise ones,and the first has left the Earth. In the next three years,the rest will join the first 36,000 km up in the sky to form the constellation of the Seven Sages to guide us on our travels. Bearing the rather staid name of IRNSS,short for Indian Regional Navigation Satellite System,this is the countrys own navigation system,like the US Global Positioning System (GPS). The first of the seven-satellite system,1A,was launched from the Satish Dhawan Space Centre at Sriharikota last week on a polar satellite launch vehicle (PSLV)the rocket that launched Chandrayaan-1 to the Moon. By 2016,the remaining six,starting with IRNSS 1B,will be up in the sky,with approximately one launch every six months. Four satellites will be placed in geosynchronous orbits and three in geostationary orbits over the Equator. The IRNSS-1A is expected to remain operational for 10 years. Once all seven are in place,the system,expected to cost over Rs 1,000 crore,would cover the vast subcontinent,offering navigational guidance on road,in water and in the sky,and also on smartphones,with an expected accuracy of 10-20 metres according to officials at the Indian Space Research Organisation. IRNSS satellites will transmit signals in two frequency bands,L5 and S,and provide two types of servicethe Standard Positioning Service for civilian use and a Restricted Service to be made available only to the military. With a reach of about 1,500 km around IndiaISRO is open to adding more satellites to expand the coveragethey would also help to map and survey,monitor and warn,and assist in agriculture and research. But that is not all. Besides latitude,longitude and altitude,what a geo-spatial positioning system also provides is the critical dimension of time. At present,Americas GPS,a free service available internationally,leads in providing precision time to communication networks,financial institutions,power grids and laboratories across the globe. Inherent in the idea of an independent positioning system is the idea of an independent time standard. On board the first satellite is a Rubidium standard,an extremely accurate atomic clock that is precise to nanosecond levelsa billionth of a second. There will be more such clocks on board the other satellites as well,eventually forming the network that would truly define Indian Standard Time. But how different is the system from existing onesthe most popular GPS,its closest rival the Russian GLONASS,the stuttering European Galileo or the nascent Chinese BeiDou? For people,there is little difference except that they need not depend on a single navigational system. Enhanced accuracy and availability can be ensured by using signals from different constellations. A navigational satellite emits radio waves that contain information about the satellites orbital position at a particular time. Given the velocitythe speed of lightand the time taken for the signal to be trasmitted between two points,the distance between them can be calculated. A GPS receiver that is locked on to several satellites at once is thus able to compute latitude,longitude,altitude,and time. The IRNSS will,however,need special receivers,which are currently under development. For the country,the key word in project IRNSS,ever since it was sanctioned in 2006,is independent. The system,largely,is the countrys back-up in space at the time of a crisis. Space programmes have always been associated with defence. A navigation system,too,has a military application. It guides,in times of need,missiles,smart bombs and fighter planes at an even higher level of precision. It would hence be a strategic mistake not to have control over navigation systems. Despite making advances in weaponry,both acquired and developed,like BrahMos,the capability to strike would greatly depend on having a reliable,independent system in place. In its latest BrahMos missile,India has therefore included both GLONASS and GPS receivers. India is not looking to gain absolute independence in navigation,as it will entail redundancies when it comes to civilian use. This is where an improved GPS system comes into the picture. The GPS-aided GEO Augmented Navigation (GAGAN) is in the works,with two satellites already in orbit. Once complete,it would help Indias aviation sector that has 85 airports and 456 airfields in operation. For commercial users,existing facilities and their augmented versions would do the job just as well. But for the country,IRNSS is a technological leap in the right direction.
