Earth Observations System (EOS) is an important space infrastructure that has been established by the Department of Space (DOS). The system, which was commissioned in 1988 with the launch of Indian Remote Sensing SatelHte, IRS• lA, has the world's largest constellation of five satellites (IRS•} C, fRS•l D. IRS-P3, IRS-P4 and TES) presently in ' operation. It provides space-based remote sensing data in a variety of spatial resolutions and spectral bands meeting the needs of various applications.
The EOS definition, development, operation and ita application are co•ordinated by the National Natural Resources Management System (NNRMS), for which DOS is the nodal agency. NNRMS is an integrated resource management system a imed at optimal utilisation of country's natllral resources by a proper and systematic inventory of resource availability using EOS data in conjunction with conventional techniques. NNRMS is supported at the national leve l by the Planning Committee of NNRMS (pC•NNRMS), which provides guidelines for implementation of the system and also oversees the progress of remote sensing applications for natural resources management in the country.
The NNRMS activities are guided by ten Standing Committees, namely, (i) Agriculture & Soils, (ii) Bio-Resources (iii) Geology and Mineral Resources (iv) Water Resources (v) Ocean Resources (vi) Cartography & Mapping (vii) Urban Management (viii) Rural Development (ix) Technology & Training and (x) Meteorology. Each of the Standing Committee is chaired by Secretaries of the re spective Government departments and includes experts from major Modular Opto-electronic Scanner (MOS) user departments.
SPACE SEGMENT Satellites in Operation:
There are 5 spectral (nm) 765-768 log•IOto U;00-1700 Indian Remote Sensing (IRS) satellites in Swath (km) operational at.. present• IRS•lC, IRS-lD,IRS•P3, IRS-P4 and Technology Experiment Satellite X-ray Payload (TES). IRS-IB, which was launched in August - Three Pointed Proportional Counters (PPC) 1991. was decommissioned during the year in Energy range of2-20 keY after it served for more than 10 years, even . X•ray Sky Monitor (XSM) 10 Energy though it was designed for only three years life. range 2-8 ke V IRS-1C and IRS-1D: IRS-IC and IRS-ID. IRS-P4 (OCEANSAT).• IRS•P4 spacecraft was which .r. identical, were launched in launched on board PSLV-C2 10 May 1999. It December 1995 .nd September L997 carries the following payloads: respectively. They carry three cameras. Ocean Colour Monitor (OCM) Panchromatic Camera (PAN), Linear Imaging Sensor Parameters Specifications Self Scanner (LISS-III) and Wide Field Sensor Spatial Resolution (m) 360 (WiFS) with foUowing specifications: Swath {km) 1'120 PAN ~ WLl~S Repetitivity (days) 2 VNIR " SWIR Local time of equator 12 nool1 1 ~lIa ,. 23,1) 70.5 ". Crossing (bra) ReaoIuUon {mJ SV0'8lh (\on) 7. '" , .. 81. Spectral Bands (nm) 402-422; 433•453; Speroal Band 0.6•0.76 0.62•0.159 1.~1.7 0.62•0.68 480-500; 500-520; (MlCI'OMJ 0.62•0.68 0.77-0.86 545-565: 660-680; 0,77•0.86 745-785: 845-885 IRS-PS IRS•P3 w8s1aunched Multi-frequency Scanning Microwave 10 March L996 on board India's PSLV. It carries n Wide Field Sensor Radiometer (MSMR) (Wi.FS), Modular Opto-electronics Scanner Frequency (Gflr.) 6.G 10.6 '8 21 (MOS) developed by the German Space Agency. SIl8tJ.a1 Re80lubon (kro) '20 80 40 40 DLR, and an X•ray astronomy instrument.
The Swath (km) 1360 details of the payload are as follows: Temp. Resolution 1,0 dCR K IRS-P3 is operated in earth pointing mode for the operation ofWiFS and MOS and Dynamic Temp. Range 330 dog J.: In the sky• pointmg mode for the operation of the X-ray Technology Experiment Satellite (TES) instrument. TES was launched on board PSLV -C3 on October Wide Field Sensors (WiFS) 22, 2001. The satellite, weighing lL08 kg, is an llond •3 0.62•0.68 micron~ experimental satellite to demonstrate and Bond-'I 0.77•0.86 microns validate, in orbit, technologies that could be Band•~ I.M-1.70 microns used in the future satellites of ISRO. Some of Ground nllJOlution 182xl66 (red .. d the technologies that are being demonstrated m m near TES are attitude and orbit control system, high mfn-red); 246xl86 m (shorlwo\'1! infratorque reaction wheels, new reaction control red) system with optimised thrusters and a single SWBth 810 km propellant tank, light woi!ight spacecraft structure, solid state recorder, X-band phased 143 array antenna, improved satellite positioning system, miniaturised TIC and power system and, two mirror on a:'cis camera optics. TES also carries a panchromatic camera with a spatial resolution of 1 m.
FOLLOW-ON SATELLITES FOR EARTH OBSERVATION
IRS-P6 (RESOURCESAT-l), IRS•P6 (RESOURCESAT•l) is launched by PSLV in 2002•03. It will carry the following payloads: (i) a multi•spectral camera USS•3 providing 23.5 m spatial resolution in four spectral bands with a swath of 140 km, (ii) a high resolution multi•spectral camera LISS•4 providing 5.8 m spatial resolution operating in three spectral bands and (iii) an Advanced Wide Field Sensor (A WiFS) with a spatial resolution better than 70 m in three spectral bands and providing a swath of 740 km. IRS•P6 will not.only provide service continuity to IRS•1C and IRS•IO but also enhance the service capa,bilities in the areas of agriculture, disaster management, land and water resources, with better resolution imageries. mS-P5 (CARTOSAT -1), lRS•P5 is launched by PSLV in 2003•04.
The satellite is primarily intended for advanced cartographic applications. IRS•P5 will have two panchromatic cameras on board with 2.5 m resolution with a swath of 30 km each. These cameras are mounted with a tilt of +26 deg and -5 deg along the track with respect to nadir to provide stereo pairs of images needed for the generation of Digital Terrain Model (OTM)/ Digital Elevation Models (OEM) of the required regions. The data products will be used for cartographic applications, cadastral mapping and updating, land use and other GIS applications. The satellite has a revisit capability of 5 days, which can be realised by steering the spacecraft about roll axis by 26 degrees. During tbe year tbe equipment panel design bas been finalised. Various components are under development and testing.
Ground Segment: The ISRO Telemetry, Tracking and Command Network (lSTRAC) monitors and controls aU the IRS satellites besides other low earth orbit satellites. ISTRAC has a ni!twork of ground stations located at Bangalore, Sriharikota, Port Blair. Thiruvanantbapuram, Mauritius and Bearslake witb multi•mission Spacecraft Control Centre at Bangalore.
TIC stations at Brunei and Biak have a]so been added recently. ISTRAC. at present tra.cks, monitors and controls IRS•IC,IRS•ID, IRS•P3, JRS•P4 and TES. ISTRAC was extensively used for conducting various demonstrations on TES. The payload operations on IRS•IC and IRS•ID are carried out over the Inman stations at Shadnagar in India as wp.ll as foreign data reception stations at Fairbank (USA), Seoul, Korea, Cotopaxy (Ecuador), Dubai, NeustraJitz (Germar.y), Norman (USA), Tokai (Japan) and Riyad (Saudi Arabia). On an average abou~ 350 to 400 payload operations are being carried out per month. IRS•P3 payload operations are being carried out for about 250 times per month over Shadnagar in India, Neustralitz and Wallops (Germany) and Maspolamas (Spain).