Satellite imagery has been put to use in economic and developmental activities, thus realising Vikram Sarabhai's dream of applying advanced technology to the real problems of society.
INDIA'S Earth Observation Programme (EOP) began with the Bhaskara satellite launched in 1978, and became operational with IRS-1A, the first Indian Remote sensing Satellite (IRS), launched in 1988. The EOP is the mainstay of the National Natural Resources Management System (NNRMS), which aims at optimal use of the country's natural resources and also supports development programmes. The National Remote Sensing Agency (NRSA) in Hyderabad acquires, processes and distributes data, besides executing application projects in collaboration with users, including State governments and private organisations.
India's IRS-1C, IRS-1D, IRS-P 3, IRS - P4 (Oceansat) and TES (Technology Experiment Satellite) form the largest constellation of remot-ensing satellites in space today and are as good as the French SPOT or the United States' Landsat.All the five satellites were built by the ISRO Satellite Centre (ISAC) in Bangalore and have in many ways realised the dream of Dr. Vikram A. Sarabhai, the father of the Indian space programme. "We must be second to none in the application of advanced technologies to the real problems of man and society, which we find in our country," Sarabhai had said.
Keeping the thrust on the EOP is Dr. P.S. Goel, Director, ISAC. " We are primarily an application-driven programme. Remote sensing has got multiple dimensions. Our focus is on resources," he said. According to Dr. Rangnath R. Navalgund, Director, NRSA, the major application areas of India's remote sensing programme are sustainable agricultural production; environment auditing; monitoring the country's 7,500-km-long coastline; managing floods, cyclones, droughts, landslips and forest fires; oceanography; infrastructure development; and weather forecasting.
The increasing population demands a continuous increase in the country's foodgrain production, which now stands at 210 million tonnes. Remote sensing can tell us how to make the 142 million hectares that come under agriculture in India yield more. Said Dr. V. Jayaraman, Director, EOS (Earth Observation System), and Programme Director, ISRO GBP (Geosphere Biosphere Programme): "We have to go for remote sensing-based studies on land use, soil and water conservation measures, and watershed management." Under Crop Acreage and Production Estimation (CAPE), the yield is predicted a month ahead of the harvest by taking into account the number of acres cultivated, water availability, health of the crops and so on. The Union Department of Agriculture and Cooperation (DAC) used the CAPE results to assess kharif production during the drought in 2002.
The DAC has undertaken a major project to identify suitable soil for horticulture development in the north-eastern region. "Before the DAC took up this project, they asked us to identify the suitable areas in the whole of North-East", said Dr. V.S. Hegde, Deputy Director (Applications), EOS, and Associate Director, Disaster Management Support (DMS). This was done with the help of remote sensing data. Watersheds are also monitored with such data to check water run-off and washing away of top soil.
Disaster management, including damage assessment and mitigation, is another important area where IRS imageries play a valuable role. Pictures of advancing cyclones beamed by INSATs have in the past several years helped evacuate people and cattle quickly from the coastal areas in Andhra Pradesh and Orissa before the cyclones struck. Loss of life was, therefore, minimal. About the Disaster Management Support programme, Dr. Hegde said: "Our objective is to give information on a real-time basis. The data help in disaster mitigation. We want to empower the DMS with timely information."
Satellite imageries are used to monitor the environment, including the extent of forest cover, and wetland conservation. "Forests, wetlands, coastal zones, deserts, glaciers and watersheds are all monitored: whether they are undergoing degradation and if so what steps should be taken to arrest it. Remote sensing plays an important role, providing data at frequent intervals and different scales," said Dr. Navalgund.
Fishermen harvest more fish, thanks to satellite data that measure the chlorophyll in phytoplanktons. Phytoplanktons form the food for zooplanktons, which, in turn, are food for small fish, which are eaten by big fish. Thus phytoplanktons help in locating schools of fish in the sea. Fishermen's associations are given the information through the State governments and the feedback from them is that by using satellite data the fishermen harvest twice the usual catch. The imageries also help prevent the overexploitation of fishing grounds and ensure that breeding grounds and young fish are left untouched.
According to Dr. Hegde, 64 command areas in the country, including Nagarjuna Sagar and Shriram Sagar in Andhra Pradesh and the Tungabhadra in Karnataka, are being monitored. "This is a project of societal importance," he said. Wastelands, too, have been mapped. Satellite data have revealed that there is 63 million hectares of wasteland in the country. It was found that 40 million hectares of this could be upgraded into cultivable land. Based on these data, the wasteland reclamation project has been reoriented.
Remote sensing applications will receive a boost when the PSLVs launch a series of IRS satellites from Sriharikota in the coming years. They include RESOURCESAT to be launched in October, a series of CARTOSATs for mapping applications, and Megha-Tropique satellites, in collaboration with France. India will climb new heights in remot-ensing when the ISAC-built RISAT (Radar Imaging Satellite) takes to the sky. Said Dr. Jayaraman: "RISAT can look through the clouds, day and night. We shall be able to get good information on soil moisture. Flooded areas can be mapped. This will lead to newer applications."
The frontiers of India's space programme are rooted firmly in progress achieved on the ground. Dr. Goel summed it up: "We are the world leaders in remote sensing applications. Over the years, we have completely tuned our space programme to suit the developmental needs of the nation."