Human-made technology that stores data about an object without coming into direct contact with it.
ADVANTAGES OF REMOTE SENSING.
There are many advantages of obtaining imageries of the entire earth or a part of it by remote sensing. Important among them are listed below:.
1. For sizable areas within the field of view of the sensor, spacecraft coverage is truly synoptic, because the high altitude and speed of the spacecraft permit the scientist to obtain information of large areas at a single instant of time.
2. It is possible to get real time analog and digital data.
3. Once can get information on short notices, on impending diseases, forest fires, disaster areas such as earthquakes, storms etc.
4. Satellite images are permanent records providing useful information in various wave bands.
5. Repetitive coverage helps in monitoring changes which occur slowly and in remote areas such as melting of glaciers, drying up of water bodies, movement of people, etc.
6. It is less expensive considering the long-term application of information.
7. The long duration of space flights and all weather operations are highly advantageous aspects of remote sensing from outer space.
8. Technical and operational advantages result from the precise regularity of spacecraft motion, from the lack of vibration, and from the heigh rate of movement.
9. Remote sensing facilitates easy data acquisition over inaccessible areas like Amazon forest, Himalayan peaks, and snow covered polar areas.
10. It provides long term record of earth surface information to be utilized later at any given time. thus, accurate data on current inventory and rate of depletion furnishes the basic information required to anticipate forthcoming events and thus to prepare contingency plans. HISTORY OF REMOTE SENSING. HOW IT ALL BEGAN?
The roots of remote sensing lie in five significant developments in scientific endeavours of man. The first was the invention of airplane, which aroused the desire to fly to the outer space beyond the gravity of the earth , the second was the technology to send unnamed and then manned satellites around the earth, and third was the development of sensors, which could catch the electromagnetic waves emanated from the earth, fourth was the development of cameras fitted with such sensors to convert the waves into photographs, and the fifth was the development of technique to interpret these photograph into maps.
The story of Right brother who are known as fathers of aeroplanes is known to all and need not be repeated here.what is important is the during the second world war airplanes were used to bomb enemy targets by physically looking down at the targets. After the war , cameras were fitted to airplanes to take photographs of floods, forest fire, earthquakes,enemy position and many other events and happening. as we have discussed this in the previous chapter, air photography has now become a first step in physical planning and development.
Rocketry to go beyond the reach of the aeroplanes can be said to the precursor of in development of artificial satellites. During the last century, three scientist in three different countries made significant contributions.They were Herman oberth in Germany, Konstantin Tsiolkovsky in Russia, and Robert Goddard in the USA. During the second world war, London was attacked by V2 missile, which had a range of 200 miles and travelled at 3,500 miles an hour.
After the war, the USA and the USSR proceeded further. On October 4, 1957. The USSR launched its first artificial satellite spuntik 1 into space and on August 12, 1961 Lt.yuri Gagarian becam the first human to orbit the earth on Vostok 1. He went round the earth for 108 minutes at 327 km above the earth.
On January 28, 1958, the USA put into orbit its first satellite. Explorer 1. After two years in 1961 Alan shepherd became the first American to fly in space. John Glenn became the first American to orbit the earth on February 20,1962. On July 20,1969, Neil Armstrong landed on the moon. Six more missions to moon were accomplished before the end of 1972.
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