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RTD info logoMagazine on European Research N° 44 - February 2005   
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EARTH AND SPACE
Title  Ensuring emergencies do not become disasters

Observation satellites are equipped with passive (optical systems) and active (radar and laser) sensors offering ever-improving levels of performance. The fundamental benefit of these space sensors lies in the repetitiveness and regularity of the images and data they transmit. They are used at two major stages in the process of managing risk or emergency situations: forecasting and prevention. 

Prevention seeks to construct diagnoses or scenarios of present or future environmental situations. It is based on taking pictures and collecting measurements, in particular in problem or risk areas. The data supplied by the various satellites must then be evaluated, a process that involves the exchange of large quantities of data and the ability to compare them. (This is why we need a central ‘system of systems’). The aim is to achieve a precise mapping of the specific characteristics of various parts of the globe at local or wider levels, to update regularly geographical information systems, to establish comparative models on the basis of identical situations, and to manage the means to limit the scale and gravity of natural and man-made risks (pollution, fires, etc.). 

Forecasting relates to the short-term, ranging from 24 hours to a few days. The most familiar example is the enormous progress achieved by meteorology thanks to the observations of geostationary (at 35 800 km over the Equator) and polar satellites (which pass over the poles at an altitude of between 500 and 1 000 km). The pictures and data transmitted – coupled with the information provided by terrestrial networks – feed the computer models. These are then used to discern changes, pinpoint the origin of a phenomenon, and continuously monitor developments.

 

Flooding in the Saône Valley (FR) in 2001:On the left, rising rivers. In the centre, floods. On the right, land affected by floodwaters. © ESA
Flooding in the Saône Valley (FR) in 2001. On the left, rising rivers. In the centre, floods. On the right, land affected by floodwaters.
© ESA


Whether in the event of a storm or cyclone, spreading oil slick, tidal wave, floods or forest fires, satellite observations help to organise a response and optimise action to save lives. To achieve this, large volumes of data must be processed in real time so as to extract the pertinent information rapidly.  

In the case of earthquakes , however, forecasting is still at the experimental stage. A lot of research is currently being conducted in the hope that, one day, satellites will be able to sound a warning before earth tremors or volcanic eruptions actually occur. This will be the result of ‘listening’ to the cracking of rocks in zones of high seismic activity, measuring temperature fluctuations on coastlines, and analysing electromagnetic disturbances around the Earth.(1)

(1) See RTD info n°43, The furies of the Earth.

    
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