Today, the Indian Space Research Organisation (ISRO) will launch the first of seven satellites that will provide the country with an independent navigation satellite capability.
A navigation satellite system uses a cluster of spacecraft that regularly transmit signals.
Suitably equipped receivers can then use that data to work out their exact position. Satellite-based navigation has, over the years, become indispensable, with a multitude of both civilian and military uses. Vehicles, big and small, as well as aircraft and ships increasingly find their way using such navigation devices. People these days turn to map and location-based services on their mobile devices.
World scene
The best known and currently the most widely used navigation satellite system is the U.S. Global Positioning System (GPS), which became operational two decades ago. Russia too offers global coverage with its Global Navigation Satellite System (GLONASS). Europe is establishing its own global system, Galileo. Although the full constellation will be ready only by 2019, it plans to begin some services with a reduced number of satellites by the end of next year.
Last December, China announced operational services from its BeiDou Navigation Satellite System over that country and surrounding areas. It intends to launch more satellites and expand the system for global coverage by 2020. Japan has already launched the first of three satellites for its regional system that will augment GPS services.
Footprint
With seven satellites, the Indian Regional Navigation Satellite System (IRNSS) will broadcast its signals primarily over India and to about 1,500 km beyond its borders.
ISRO planned to put the full constellation of satellites into orbit by the financial year 2014-15, according to the space agencys chairman, K. Radhakrishnan.
If necessary, the coverage area around India could be enhanced by adding four more satellites, he told The Hindu .[ As I expected]
As to why India needed its own satellite navigation system, he responded:
It is essentially to ensure that you have an assured service when you want it. If you are dependent on a foreign navigation signal and then you are in dire need, there could be a situation [it may] not be available to you.
That sort of concern has also been voiced in Europe, which, although a close ally of the U.S., still felt the need to have its own navigation satellites. Much to Americas annoyance, European institutions began moves in the late 1990s to establish the Galileo system.
Defence, prime factor
The European Commission noted that Galileo would ensure Europes independence in a sector that had become critical for its economy and the well-being of its citizens. We have become so dependent on services provided by satellite navigation in our daily lives that should a service be reduced or switched off, the potential disruption to business, banking, transport, aviation, communication, etc to name but a few, would be very costly.
Military operations rely heavily on satellite navigation, and Indias defence requirements appear to have played an important part in the decision to establish an independent system. The operator of a foreign system can choose to deliberately degrade the accuracy of its signals, as the U.S. reportedly did with the freely accessible GPS signals when invading Iraq.
Apart from signals that anyone can utilise free of cost, satellite navigation systems, including the Indian one, provide an encrypted service that is restricted to those authorized to receive it.
As part of Indias modernization of its armed forces, a satellite system of its own gave the country redundancy and reduced dependence on outside agencies for a key technology, observed Wing Commander Ajey Lele, a space and national security analyst at the Institute for Defence Studies and Analyses in Delhi.
Moreover, satellite navigation had huge civilian applications, he pointed out. With India developing both economically and technologically, this factor too would have influenced the decision to establish the IRNSS.
The applications of global navigation satellite systems are potentially enormous, according to the consultancy firm, Frost & Sullivan. The industry view is that it is a massive market waiting to take shape and what we see of its present use can be considered a tip of the iceberg.
The global applications market would grow from 65 billion in 2012 to about 134 billion in 2021, it estimated in a report issued some months back.
Indias IRNSS, along with GAGAN, is set to serve a potentially huge market across the sub-continent, the report noted. (GAGAN, an abbreviation for GPS Aided Geo Augmented Navigation, is a satellite-based system implemented jointly by ISRO and the Airports Authority of India to improve GPS accuracy over the country as an aid for aviation. (For more details, see GAGAN making GPS more accurate, Science & Technology page, The Hindu , June 2, 2011.)
Interoperability
The worlds navigation satellite operators increasingly find it beneficial to make their systems work together. Interoperability, which allows receivers to take signals from more than one system, is catching on.
Especially in situations where signals from one constellation of satellites might not be readily available, such as when those signals are obstructed by tall buildings in an urban setting or in mountainous terrain, a receiver that is able to utilise multiple systems can function better and more accurately.
A combination of Galileo and GPS receivers would allow far more accurate position determination, noted a 2011 review of the European system. The same would be true if the BeiDou and GPS systems were used together, noted a presentation made at a conference held in Shanghai, China, two years back.
Ensuring interoperability among navigation satellite constellations and integrating their services was going to be the primary challenge for realising their full potential, according to the Frost & Sullivan report.
ISRO was working with industry to develop receivers that worked with the Indian system, said the space agencys chairman.
Some of those receivers would be designed to take signals from IRNSS as well as another constellation.
An Indian mission to another frontier in space | idrw.org
