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Aviation History
1969
1969 - 1039.PDF
948 FLIGHT International, 5 June 196 Earth-resource satellites discussed THE BRITISH NATIONAL COMMITTEE ON SPACE RESEARCH arranged on May 20 a discussion meeting at the Royal Society to consider the potentialities of satellites for surveying the Earth's resources. This meeting had been spon sored toy the first of three working groups which have been set up in the last year, under the auspices of the committee to examine certain space activities in the neighbourhood of the Earth, one of these being Earth resources satellite systems. It was a unique meeting, for the first time in Europe, of all the establishments, organisations and companies in the United Kingdom which might have an ultimate user-interest. The morning of the meeting was devoted to three presenta tions on certain aspects of these systems. The first paper, by Dr Naugle of NASA, covered his organisation's evolving pro gramme to develop Earth-resource surveys from space. Dr Naugle reviewed the complete range of possibilities of such satellites, covering the areas of geological surveys for mineral deposits, the use of satellites for agricultural surveys to deter mine both the health and state of growth of crops and the - world's forests (with the added advantage of early-warning detection, of fires), applications to oceanography, and the ifher many aspects that now appear possible. He referred to experiments in America using ground sites known characteristics as a check on the signatures measured airborne and spaceborne sensors. Against this background, A had how invited 16 American companies to bid for an •resource technological satellite project (which has been 1 since it was first conceived in 1966) as a specific means lining sensor characteristics and requirements related •resource activities. It was expected that this NASA ellite would be put out to a contractor within the 'onths with a launch date at the end of 1971 or the f 1972 for the first flight, was not described in great detail, but it would 3'icon TV cameras which would examine three of the spectrum, using a flying-spot scanner Means of measuring the information and trans- o Earth. The vidicons would cover an area miles by 100 miles directly under the satel- ie placed in a 500 mile circular orbit. The ' detail expected from this particular satel- 500ft. Other instruments such as radio- 'ooking radar were being examined by .' rcraft programmes and would be intro- •)grammes at an appropriate stage. Dr •5 United States considered the poten- ^e satellite programme as being most nmended at this stage that it would w to invest significant money and \n or development of sensors and ?one into the whole thing much for example, that the question vet been fully resolved; and rders needed for this system with audio bandwidths. A •r the large volume of data illite and, until this had d not be sure what proo- >y Dr Davies of the ved electronic sensors for Earth-resource surveys by satellite. He took as a typical example a 400km circular orbit, at which height the satellite would have a linear speed of approximately 7.5km/sec; the Earth's surface would appear to rotate underneath at l°/sec.. Starting with cameras, he then examined various sensors that seemed to have a survey potential. Panchromatic film having a resolution of 40 lines/mm was available now, and these films would undoubtedly have considerable potentiality. Tele vision, of course, would be easier from a logistic point of view, and various types of television were described, together with image intensifiers to enhance the sensitivity of the TV camera in low-light conditions. Infra-red would seem to provide a very important type of measurement for Earth-resource measurements and false colour technique had already revealed useful information. Infra-red linescan was another application of sensors with . considerable potential, and sideways-looking radars also appeared to offer some potential in this area. The speaker illustrated his argument by photographs which had been taken by IR and radar, and it was. quite clear that there was a considerable amount of potential in the development of such devices which could then be calibrated and used for actual measurement purposes. The third paper was presented by Dr Van der Meer Mohr of the International Institute for Aerial Survey and Earth Sciences in Delft. His paper covered the potential use of space photographs for geological interpretation and mapping. Dr Van der Meer Mohr examined the relationship between space photographs vis-d-vis aerial photographs, and pointed out that small-scale coverage could frequently be very useful and cer tainly more economical in time and effort than the larger scale presentations obtained from lower levels by aircraft. Space photographs and mapping He identified the advantages which Dr Davies and others had already mentioned concerning the value of a vertical view of the Earth in one frame, rather than the variations in light ing conditions caused by mosaic patterns put together by air craft techniques, but thought that stereographic techniques would probably not be applicable owing to the height of the spacecraft in relation to the area being examined. In review ing geological aspects particularly, he indicated that space photographs had already revealed- tnany important features which otherwise would not have been available; and, in general, large features, faults in the earth for example, showed up better (if not uniquely) on space photographs than by aerial survey techniques. In certain cases, space photographs had ( revealed more information than had previously been available. Obviously there were some limitations in the use of space photographs and it seemed that space and aerial photography would be essentially complementary in monitoring and observ ing the resources of the world. In terms of cartography Dr Van der Meer Mohr felt that photographs could be most helpful and, because of the height, in many cases could be treated as small-scale maps. Certainly space photographs pro vided the means of synoptically mapping areas which had not hitherto been practical in terms of aerial surveys. The afternoon was devoted to a general discussion by the participants on the potentialities of Earth-resources systems: Mr King from Australia was a little concerned at the possible cost that might be involved in surveying from space, com pared With the typical large mining company's research budget for a year, which perhaps might only be S>2 million. But he agreed that space photographs appeared to offer considerable potential in certain areas and he illustrated this by showing a photograph of Iran which had been taken on a Gemini flight. This indicated two small mineral deposits which had since been confirmed by a geological survey. Professor Cole presented several slides to describe even more potentialities than had been mentioned by the morning speakers and emphasised the importance of the use of photographs; in her own particular field, she had been interested in relating the natural vegetation of a region to the mineral composition of the terrain itself. Some new facts had already emerged from space photographs. One amusing incident had been an analysis of a photograph taken off the coast of the Gulf of California, in which American interpreters had noticed dis turbed sediment at the efflux of rivers into the sea, and (on
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