Earth Observation System
The Indian Earth Observation (EO) System which was commissioned in 1988 with the
launch of Indian Remote Sensing satellite (IRS-1A) has received further fillip during the year with the successful launch of CARTOSAT-2 by PSLV-C7 on January 10, 2007. The definition, development, operation and application of EO are overseen by the National Natural Resources Management System (NNRMS) with DOS as the nodal agency.
IRS System
The Indian Remote Sensing Satellite system is the largest constellation of remote sensing satellite in operation today in the world. With the launch of CARTOSAT-2, the constellation now has six satellites in operation – IRS-1D, OCEANSAT-1, Technology Experiment Satellite (TES), RESOURCESAT-1, CARTOSAT-1 and the latest CARTOSAT-2. All these are placed in polar sun-synchronous orbit and provide data in a variety of spatial, spectral and temporal resolutions to enable several applications to be undertaken which are relevant to national development.
Satellites in Operation
CARTOSAT-2
Launched by PSLV-C7 on January 10, 2007, CARTOSAT-2, is an advanced remote sensing satellite carrying a panchromatic camera capable of providing scene specific spot imageries for cartographic and other applications. The satellite has high agility with capability of steering along and across the track up to + 45 deg. It was placed in a sun synchronous polar orbit of a nominal altitude of 635 km. The panchromatic camera is designed to provide imageries with one meter spatial resolution and a swath of 10 km. The satellite is configured to provide multi-scene imaging capability during a pass.
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| CARTOSAT-2 focal plane alignment |
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| CARTOSAT-2 |
Some of the new technologies developed for CARTOSAT-2 mission include: two mirror on axis single camera using Carbon Fibre Reinforced Plastic (CFRP) based electro-optic structure with 12,000 Charged Coupled Devise (CCD), large size light weight zerodur mirrors, indigenous JPEG like data compression with rate regulation, advanced solid state recorder, bus management unit housing telemetry, tracking and command, attitude and orbit control system, sensor processing, thermal management, power monitoring, high torque reaction wheels, high performance DTG based IRU and high performance star sensors.
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| CARTOSAT-2 solar panel deployment test |
The cameras on board CARTOSAT-2 were switched on January 12, 2007.
CARTOSAT-1
CARTOSAT-1 was launched into a 617 km polar sun-synchronous orbit in May, 2005 by PSLV-C6. The satellite carries two panchromatic cameras – PAN (fore) and PAN (aft) – with 2.5 meter resolution providing a swath of 30 km. The cameras are mounted with a tilt of +26 deg and -5 deg along the track with respect to nadir so as to provide stereo pairs of images that can be used to generate Digital Terrain Model (DTM)/Digital Elevation Models (DEM).
The data from CARTOSAT-1 are used for cartography, cadastral mapping updation, land use and GIS applications.
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| Three dimensional view of Jaipur generated from CARTOSAT-1 data |
The satellite has solid state recorder for data storage. The imaging operations were started in May, 2005.
RESOURCESAT-1
Resourcesat-1 was launched on board PSLV-C5 in October 2003. It is placed in 820 km high polar Sun Synchronous Orbit. Resourcesat-1 carries three cameras, they are:
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| Sprinkler irrigated area in Saudi Arabia captured by RESOURCESAT-1 camera |
• A high resolution Linear Imaging Self Scanner (LISS-4) operating in three spectral bands in the Visible and Near Infrared Region (VNIR) with 5.8 metre spatial resolution and steerable up to + 26 deg across track to obtain stereoscopic images and achieve five day revisit capability.
• A medium resolution LISS-3 operating in three spectral bands in VNIR and one in Short Wave Infrared (SWIR) band with 23.5 metre spatial resolution with 142 km swath.
• An Advanced Wide Field Sensor (AWiFS) operating in three spectral bands in VNIR and one band in SWIR with 56 metre spatial resolution and a combined swath of 730 km achieved through two AWiFS cameras.
Resourcesat-1 also carries a Solid State Recorder to store the images taken by its cameras, which can be received later by the ground stations.
IRS-1D
Launched in September 1997, IRS-1D carries three cameras, Panchromatic Camera (PAN), Linear Imaging Self Scanner (LISS-III) and Wide Field Sensor (WiFS). PAN has a spatial resolution of 5.8 metre and provides a swath of 70 km. LISS-III has a spatial resolution of 23.5 metre in VNIR and 70.5 metre in SWIR bands providing swaths of 142 km and 148 km respectively. WiFS has a spatial resolution of 188 m and a large swath of 810 km.
OCEANSAT-1
OCEANSAT-1, intended to study physical and biological aspects of oceanography, was launched on board PSLV-C2 in May 1999. It carries an Ocean Colour Monitor (OCM) and a Multi-frequency Scanning Microwave Radiometer (MSMR). OCM operates in 402-422, 433-453, 480-500, 500-520, 545-565, 660-689, 745-785 and 845-885 nm bands with 360 metre spatial resolution and 1420 km swath. At present, OCEANSAT-1 is used to collect data from its OCM.
Technology Experiment Satellite (TES)
TES was launched on board PSLV-C3 in October 2001. The satellite is intended to demonstrate and validate technologies that could be used in the future cartographic satellite missions. Some of the technologies demonstrated in TES are attitude and orbit control system, high torque reaction wheels, new reaction control system with optimised thrusters and a single propellant tank, light weight spacecraft structure, solid state recorder, X-band phased array antenna, improved satellite positioning system, miniaturised TTC and power system and two-mirror-on-axis camera optics. TES also carries a panchromatic camera with a spatial resolution of 1 m.
Forthcoming Satellites
OCEANSAT-2:
OCEANSAT-2 is envisaged to continue the service of OCEANSAT-1. It will carry an Ocean Colour Monitor (OCM) and a Ku-band pencil beam scatterometer.
In addition, it will carry radio occultation sounder for atmospheric studies (rosa), developed by the Italian Space Agency (ASI). OCEANSAT-2 will be used for identification of potential fishing zones, sea state forecasting, coastal zone studies and provide inputs for weather forecasting and climatic studies. OCEANSAT-2 is scheduled for launch by PSLV in
2007-08 into a near polar sun-synchronous orbit of 720 km. This orbit combined with the wide swath of both payloads, will provide an observational repetitivity of two days.
OCM is an 8-band multi-spectral camera operating in the visible – near infrared spectral range. This camera provides an instantaneous geometric field of view of 360 meter covering a swath of 1420 km. There is provision to tilt OCM by + 20 deg. in the along-track direction.
Ku-band pencil beam scatterometer is an active microwave radar and operates at 13.515 GHz providing a ground resolution Cell of size 50 kms x 50 kms. It consists of a parabolic dish antenna of
1 Meter dia. which is offset mounted with respect to the yaw axis (earth viewing axis). This antenna is continuously rotated using a scan mechanism with the scan axis along the positive Yaw axis. The back scattered power in each beam from the ocean surface is measured from which the wind vector is derived.
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| Ocean Colour Monitor Camera for OCEANSAT-2 |
During the year, mainframe structure has been realised. Preliminary design review of all mainframe systems completed. OCM camera test and evaluation have been completed. Scatterometer qualification model hardware have been realized. ROSA interfaces with spacecraft systems have been finalised. Qualification model of scatterometer scan mechanism and the interface test with electronics have been completed.
RISAT
Radar Imaging Satellite (RISAT) is a microwave remote sensing mission with Synthetic Aperture Radar (SAR) operating in C-band and having a 6 x 2 meter planar active array antenna based on trans-receiver module architecture. SAR is an all weather-imaging sensor capable of taking images in cloudy and snow covered regions and also both during day and night. RISAT weighs 1,750 kg.
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| Design verification model of Synthetic Aperture Radar for RISAT undergoing near-field test |
During the year, preliminary design review for the ground segment has been completed and flight model activities taken up. The satellite is planned to be launched on board PSLV during 2008-09. Some of the new technological elements in RISAT are: 160 x 4 Mbps data handling system, 0.3 Nm (50 Nms) reaction wheels, antenna deployment mechanism, 70 V power bus, thermal control of SAR antenna and phased array antenna (with Dual Polarisation).
RESOURCESAT-2
RESOURCESAT-2 will have imaging sensors similar to RESOURCESAT-1. Payload electronics have been miniaturised to reduce the overall weight. RESOURCESAT-2 is planned for launch by PSLV in 2009-10.
During the year, the engineering model structure has been realised. Subsystem packages fabrication has commenced and payload configuration has been finalised.
Third World Satellite (TWSAT)
TWSAT is the first satellite in the micro satellite series envisaged to provide 100 kg class satellite platform for carrying payloads for earth imaging, space science, atmospheric and ocean studies. TWSAT will carry a multi-spectral camera providing images with about
36 m spatial resolution and swath of 151 km. The data generated will be transmitted to user terminals. The user terminals will be PC based systems along with RF downlink and antenna systems. The software will be capable of providing data products to standard product level with radiometric and geometric corrections.
The data will be provided free to research organisations, universities and institutions in the developing countries. TWSAT is planned for launch in 2007-08.
During the year, spacecraft configuration studies with respect to electrical elements have been carried out. Mechanical configuration of spacecraft has been worked out and preliminary thermal design completed.
Ground Segment
ISRO Telemetry, Tracking and Command Network (ISTRAC) provides Telemetry, Tracking and Command (TTC) and mission control support to launch vehicle missions and near earth orbiting satellites. An integrated network of ground stations at Bangalore, Lucknow, Sriharikota, Port Blair, Thiruvananthapuram, Mauritius, Brunei, Biak (Indonesia), Bearslake (Russia) and Svalbard and Tromso (Norway) with the Multi-mission Spacecraft Control Centre(SCC) at Bangalore has been established.
During the year, in-orbit operations on CARTOSAT-1, RESOURCESAT-1, TES,
OCEANSAT-1, IRS-1D, IRS-P3 and CARTOSAT-1 have been carried out.
IRS-1C satellite has successfully completed eleven years on-orbit life.
TTC stations at SHAR, Thiruvananthapuram, Mauritius, Bangalore, Lucknow, Bearslake, Biak, Svalbard, Tromso and Saskatoon, ISTRAC Communications, ISTRAC Computers and Preliminary Orbit Determination Systems were fully made ready during the year and successfully provided support for the PSLV-C7/CARTOSAT-2/SRE-1 missions in January 2007. ISTRAC successfully supported the in-orbit operation and recovery operations of
SRE-1. Coordination with external agencies including DRDL, HAL, Coast Guard and Navy were also in place for SRE re-entry phase support using Ship Borne Terminal and Air Borne Terminal.
ISTRAC also supported External Agency Missions – Shin Satellite Company (SHINSAT) of Thailand for IPSTAR Spacecraft operations, Galelio (GSTB-V2A) mission, SPAINSAT mission, EUTELSAT HB7A mission and Advanced Composite Explorer (ACE).
Modernisation of satellite support TTC stations including Bangalore, Lucknow, Bearslake and the satellite supporting part of Mauritius and Biak stations has been completed. An 11 m diameter antenna has been installed at Lucknow TTC station. A C/S TTC station with 11 m antenna is installed and commissioned at Biak, Indonesia. New servo systems have already been installed with one terminal each at Lucknow, Biak, SHAR and Bangalore. Indigenously developed Monitoring and Control System has been successfully implemented in TTC stations.
Satellite Data Acquisition and Processing
The National Remote Sensing Agency (NRSA) at Hyderabad is the nodal agency for reception, archival, processing and dissemination of remote sensing data in the country. NRSA acquires and processes data from all Indian remote sensing satellites like CARTOSAT-1, CARTOSAT-2, RESOURCESAT-1, IRS-1C, IRS-1D, IRS-P3, OCEANSAT-1 and TES as well as foreign satellites like Terra, NOAA and ERS. As per the Remote Sensing Data Policy, NRSA is the national acquisition/distribution agency for all satellite data within India.
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| 11 m diameter antenna established for CARTOSAT-2 at Lucknow ground station |
During the year, the ground segment has been upgraded for reception, processing and product generation from advanced missions like CARTOSAT-2, RISAT-1 and OCEANSAT-2. A new 7.5 m diameter antenna has been installed for CARTOSAT-2. New Ground Control Points (GCP) have been added to GCP library to meet the CARTOSAT-2 requirements. System upgradation has been carried out for reception of RISAT-1 data in dual polarisation and high bit rate mode.
A 4.8 m antenna and satellite reception terminal has been installed at NRSA, Balanagar and earth station Shadnagar, to support Decision Support Centre (DSC). ISRO’s Spacenet bandwidth has been enhanced for improved connectivity. INSAT meteorological data is now downloaded daily in near real-time through Spacenet network from MCF, Hassan for use in remote sensing applications.
Data archival efficiency has exceeded 98 percent during the year. A PC-based ERS data archival system has been developed. The data on browse archival system is available on Internet. An integrated multi-mission ground segment for earth observation satellites is being planned to process the chain of activities from data acquisition to product delivery and improve the turn-around-time.
During the year, about 10,500 data products were disseminated to Indian as well as foreign users. The data is available on high-density digital media. Ocean colour data is available through ISDN to major users. Data is also disseminated under International Charter and USDA. CARTOSAT-1 mono and stereo data products are available operationally.
Support is being provided to 20 International Ground Stations (IGS) for IRS data reception. IGS are being upgraded to support RESOURCESAT-1 and CARTOSAT-1 operations.
Aerial Remote Sensing
The aerial remote sensing facility of NRSA offers value-added services like aerial photography and digital mapping, infrastructure planning, scanner surveys, aeromagnetic surveys, large scale base map, topographic and cadastral mapping, etc. Two aircraft with modern navigational aids, aerial cameras and sensors are available to carry out these activities.
