Indian Regional Navigation Satellite System

The Indian Regional Navigation Satellite System or IRNSS is an indigenously developed Navigation Satellite System that is used to provide accurate real-time positioning and timing services over India and region extending to 1500 km around India. The fully deployed IRNSS system consists of 3 satellites in GEO orbit and 4 satellites in GSO orbit, approximately 36,000 km altitude above earth surface.[1] However, the full system comprises nine satellites, including two on the ground as stand-by.[2] The requirement of such a navigation system is driven because access to foreign government-controlled global navigation satellite systems is not guaranteed in hostile situations, as happened to the Indian military depending on American GPS during the Kargil War.[3] The IRNSS would provide two services, with the Standard Positioning Service open for civilian use, and the Restricted Service (an encrypted one) for authorised users (including the military).
IRNSS would have seven satellites, out of which five are already placed in orbit. The constellation of seven satellites is expected to operate from June 2016 onwards.[4][5]


Development[edit]

As part of the project, ISRO opened a new satellite navigation center within the campus of ISRO Deep Space Network (DSN) at Byalalu, in Karnataka on 28 May 2013.[6] A network of 21 ranging stations located across the country will provide data for the orbital 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.[7]
The total cost of the project is expected to be 1420 crore (US$209 million), with the cost of the ground segment being 300 crore (US$44 million). Each satellites costing 150 crore (US$22 million) and the PSLV-XL version rocket costs around 130 crore (US$19 million) . The seven rockets would involve an outlay of around 910 crore (US$134 million).[2][8][9] The IRNSS signal has been released for evaluation in Sep 2014[10]

Time-frame[edit]

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. But program was delayed.[11] India also launched 3 new satellites into space to supplement this.[12]
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 launched on 1 July 2013.[13][14] IRNSS-1B was launched on 4 April 2014 at 17:14 IST on board the PSLV-C24 rocket. The satellite has been placed in geosynchronous orbit.[15] IRNSS-1C was launched on 16 October 2014,[16] IRNSS-1D on 28 March 2015[17] and IRNSS-1E was launched on 20 January 2016.[18] Of the remaining two satellites, IRNSS-1F has a planned launch in March 2016 and IRNSS-1G should be in orbit by April 2016 [19] and by middle of 2016, India will have the full navigational satellite system in place.

Description[edit]

Approximate coverage of the IRNSS once complete
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 (GEO) at 32.5° East, 83° East, and 131.5° East longitude. The other four will be in inclined geosynchronous orbit (GSO). Two of the GSOs will cross the equator at 55° East and two at 111.75° East.[20] 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 (2492.028 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.[21]
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 (TT&C stations) to monitor the satellites with the capability of issuing radio commands to them. 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 an independent system, an Indian standard time infrastructure would also be established. 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.

Satellites[edit]

IRNSS-1A[edit]

Main article: IRNSS-1A
IRNSS-1A was the first navigational satellite in the Indian Regional Navigation Satellite System series of satellites to be placed in geosynchronous orbit.[22][23] It was built at ISRO Satellite Centre, Bangalore, costing 125 crore (US$18 million).[8][9][13][24] 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).[25] 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.[26][27] The satellite was launched on-board PSLV-C22 on 1 July 2013 from the Satish Dhawan Space Centre at Sriharikota.[13][14][28]

IRNSS-1B[edit]

Main article: IRNSS-1B
IRNSS-1B is the second out of seven in the Indian Regional Navigation Satellite System. It was very precisely and successfully placed in its orbit through PSLV-C24 rocket on 4 April 2014.[29]

IRNSS-1C[edit]

Main article: IRNSS-1C
IRNSS-1C is the third out of seven in the Indian Regional Navigation Satellite System series of satellites. The satellite was successfully launched using India's PSLV-C26 from the Satish Dhawan Space Centre at Sriharikota on 16 October 2014 at 1:32 am.[30][31]

IRNSS-1D[edit]

Main article: IRNSS-1D
IRNSS-1D is the fourth out of seven in the Indian Regional Navigation Satellite System series of satellites system. It was successfully launched using India's PSLV-C27 on 28 March 2015 at 5:19 pm.[23][32]

IRNSS-1E[edit]

Main article: IRNSS-1E
IRNSS-1E is the fifth out of seven in the Indian Regional Navigation Satellite System series of satellites system. It was successfully launched on 20 January 2016 using India's PSLV-C31 at 09:31 am.[33][34]

IRNSS-1F and IRNSS-1G[edit]

Main articles: IRNSS-1F and IRNSS-1G
IRNSS-1F will be the sixth and IRNSS-1G will be seventh of the Indian Regional Navigation Satellite System series of satellites. Their launches are planned for March 10th and 31st resp.[35][36]

See also[edit]

Indian Regional Navigation Satellite System Indian Regional Navigation Satellite System Reviewed by HamzaBashir Ahmad on 20:15:00 Rating: 5