Indian Regional Navigational Satellite System
|Indian Regional Navigational Satellite System|
|Type||Satellite navigation system|
|Accuracy||Less than 20 m over the Indian Ocean region
Less than 10 m accuracy over mainland India
|Coverage||1,500–2,000 kilometres (930–1,240 mi) around Indian landmass|
|Project Cost||16 billion (US$270 million)|
The Indian Regional Navigational Satellite System (IRNSS) is an autonomous regional satellite navigation system being developed by the Indian Space Research Organisation (ISRO) which would be under complete control of the Indian government. The requirement of such a navigation system is driven by the fact that access to foreign government-controlled global navigation satellite systems is not guaranteed in hostile situations. The IRNSS would provide two services, with the Standard Positioning Service open for civilian use and the Restricted Service, encrypted one, for authorised users (military).
As part of the project, ISRO opened a new satellite navigation center within the campus of ISRO Deep Space Network (DSN) at Byalalu near Bangalore in Karnataka on 28 May 2013. A network of 21 ranging stations located across the country will provide data for the orbit determination of the satellites and monitoring of the navigation signal.
A goal of complete Indian control has been stated, with the space segment, ground segment and user receivers all being built in India. Its location in low latitudes facilitates a coverage with low-inclination satellites. Three satellites will be in geostationary orbit over the Indian Ocean. Missile targeting could be an important military application for the constellation.
The total cost of the project is expected to be 1420 crore (US$237 million), with the cost of the ground segment being 300 crore (US$50 million) and each satellites costing 125 crore (US$21 million).
In April 2010, it was reported that India plans to start launching satellites by the end of 2011, at a rate of one satellite every six months. This would have made the IRNSS functional by 2015. India also launched 3 new satellites into space to supplement this.
Seven satellites with the prefix "IRNSS-1" will constitute the space segment of the IRNSS.
IRNSS-1A, the first of the seven satellites of the IRNSS constellation, was built at ISRO Satellite Centre, Bangalore, costing 125 crore (US$21 million). It has a lift-off mass of 1380 kg, and carries a navigation payload and a C-band ranging transponder, which operates in L5 band (1176.45 MHz) and S band (2492.028 MHz). An optimised I-1K bus structure with a power handling capability of around 1600 watts is used and is designed for a ten-year mission. The satellite was launched on-board PSLV-C22 on 1 July 2013 from the Satish Dhawan Space Centre at Sriharikota, while the full constellation is planned to be placed in orbit by 2015.
In 2014, two more navigational satellites – IRNSS-1C and IRNSS-1D would be launched. Three more navigational satellites will be launched early 2015 and by middle of 2015, India will have the full navigational satellite system in place.
The proposed system would consist of a constellation of seven satellites and a support ground segment. Three of the satellites in the constellation will be located in geostationary orbit at 32.5° East, 83° East, and 131.5° East longitude. Two of the GSOs will cross the equator at 55° East and two at 111.75° East.[dead link] Such an arrangement would mean all seven satellites would have continuous radio visibility with Indian control stations. The satellite payloads would consist of atomic clocks and electronic equipment to generate the navigation signals.
IRNSS signals will consist of a Special Positioning Service and a Precision Service. Both will be carried on L5 (1176.45 MHz) and S band (2492.08 MHz). The SPS signal will be modulated by a 1 MHz BPSK signal. The Precision Service will use BOC(5,2). The navigation signals themselves would be transmitted in the S-band frequency (2–4 GHz) and broadcast through a phased array antenna to maintain required coverage and signal strength. The satellites would weigh approximately 1,330 kg and their solar panels generate 1,400 watts. The system is intended to provide an absolute position accuracy of better than 10 meters throughout Indian landmass and better than 20 meters in the Indian Ocean as well as a region extending approximately 1,500 km around India.
Three of the seven satellites will be in geostationary orbits and the other four in inclined geosynchronous orbits. From ground, the three geostationary satellites will appear at a fixed point in the sky. However, the four geosynchronous satellites moving in inclined orbits in pairs will appear to move in the figure of '8' when 'seen' from ground. Apart from navigation, the system will help in precise time keeping, disaster management, fleet management and mapping.
The ground segment of IRNSS constellation would consist of a Master Control Center (MCC), ground stations to track and estimate the satellites' orbits and ensure the integrity of the network (IRIM), and additional ground stations to monitor the health of the satellites with the capability of issuing radio commands to the satellites (TT&C stations). The MCC would estimate and predict the position of all IRNSS satellites, calculate integrity, makes necessary ionospheric and clock corrections and run the navigation software. In pursuit of a highly independent system, an Indian standard time infrastructure would also be established.
The applications of IRNSS include terrestrial, aerial and marine navigation, disaster management, vehicle tracking and fleet management, integration with mobile phones, precise timing, mapping and geodetic data capture, terrestrial navigation aid for hikers and travellers and visual and voice navigation for drivers.
Indian Regional Navigation Satellite System (IRNSS) will be as good as any such space-based system, as India can keep a close watch of not just its boundaries, but up to 1,500 km beyond that. It works on a combination of seven satellites which would 'look' at the region from different angles, and, in the process, helps calculate from relative data, real-time movement of objects by as less as 10m.
When Pakistani troops took positions in Kargil in 1999, one of the first things Indian military sought was GPS data for the region. The space-based navigation system maintained by the US government would have provided vital information, but the US denied it to India. A need for an indigenous satellite navigation system was felt earlier, but the Kargil experience made the nation realise its inevitability.
Geopolitical needs teach that some countries can deny you the service in times of conflict. It's also a way of arm twisting and a country should protect itself against that.
This is the reasoning behind two types of services that IRNSS will be offering. The first is called Standard Positioning Service (SPS) which is for civilian use. This will have an accuracy of 20m, while the second is called Restricted Services (RS), which can detect movement of objects by less than 10m. Many weapon systems like guided missiles and bombs also use such navigation systems. An indigenous system allows the development of such capabilities in a reliable manner. There is also the need to have India's own navigation system in the civilian and commercial domain since so many critical services and businesses depend on it. A system run by another country (like GPS) may be switched off in times of crisis leading to complete collapse of certain services.
The system will be functional by the beginning of 2016. Basic navigational services wouldn't have to wait that long—they can take off with just four satellites in orbit, which will be by end of 2014. When four satellites by the end of 2014, ISRO will have an operational system and then we can go and test its accuracy to validate it.
It will be similar to the US operated Global Positioning System (GPS), Russian GLONASS, European Union, Galileo and the Chinese Beidou Navigation Satellite System (BDS).
IRNSS-1A is the first navigational satellite in the Indian Regional Navigational Satellite System series of satellites been placed in geosynchronous orbit. It was launched on 1 July 2013 on board the PSLV-C22.
IRNSS-1B is the second out of seven in the Indian Regional Navigational Satellite System. It has been very precisely and successfully placed in its orbit through PSLV-C24 rocket on 4 April 2014.
IRNSS-1C will be the Third out of seven in the Indian Regional Navigational Satellite System series of satellites. Its launch is planned in 2014.
IRNSS-1D will be the Fourth out of seven in the Indian Regional Navigational Satellite System series of satellites system. Its launch is planned in 2014.
IRNSS-1E will be the fifth out of seven in the Indian Regional Navigational Satellite System series of satellites system. Its launch is planned in March 2015.
IRNSS-1F will be the sixth out of seven in the Indian Regional Navigational Satellite System series of satellites system. Its launch is planned in March 2015.
IRNSS-1G will be the seventh out of seven in the Indian Regional Navigational Satellite System series of satellites system. Its launch is planned in March 2015.
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