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Stamp Profile EUROPA 91 JERSEY Issue Date: 24/04/1991 This year the Europa Theme is 'Europe in Space' and our latest set of stamps takes us away from Jersey into spare examining four different satellites and the purposes they serve. These spacecraft have sensors and computers to record, process, store and communicate data for monitoring the Earth's surface, i.e. remote sensing. By being able to observe large areas, an entirely new way of monitoring and analysing is available to scientists and environmental specialists, Landsat 5 appears on the first of two 20p values. Landsat refers to a series of polar orbiting remote sensing satellites, the first of which was launched in 1972 by the National Aeronautical Space Administration (NASA). This craft carries instruments, which observe the land and sea. The information sent back to earth is received by large steerable dish antennae and is stored in two ways - as computer tape or as hardcopy (photographs). Our second 2Op value shows a wider field of view and encompasses Jersey, North Western France, Southern England and the Channel. ESA's first earth resources remote sensing satellite known as ERS-1 is due to be launched shortly in a polar orbit, thus giving total global cover. It carries a wide range of sensors such as radar and other microwave sensors for studying the land and the oceans, including measurement of sea surface temperature , wave height and sea levels. Britain has been involved in every aspect of the ERS-1 programme since the late 1970's. The data received will help scientists to improve their understanding of the complex interactions between ocean, polar ice and atmosphere which are the major driving forces responsible for global weather and climate systems. Launch of ERS-1 by Ariane-4 will took place from the Kourou Space Centre in French Guyana. Technically, radar images are only obtained in black and white (grey scale) form but can be colour coded (density sliced) by computer enhancement which uses colour to characterize areas with similar densities of radar backscatter. The imaging radar will survey a strip of 80 to 100 kilometres wide no matter what the weather or time is and in this stamp Jersey is shown within the grey tone area whilst radar beam focuses, one pixel at a time on the sea off Brittany. The actual pixel size will be thirty metres as for the Landsat Thematic Mapper image on the 2Op issue. The high degree of accuracy achievable by the latest instruments will be demonstrated by the radar altimeter which can measure the 800 kilometre distance between ERS-1 and the ocean's surface with an estimated accuracy of ten to fifteen centimeters, day and night in any weather conditions. Moving on to the 26p value , we see Meteosat, the first European meteorological satellite launched in 1977 in a geostationary orbit. From its position it scans almost half the globe every half-hour transmitting data twenty-four hours a day to a ground station in Germany where the picture is enhanced and the outline of countries added. This is then sent back up to the satellite from where it was transmitted free of charge. A time table is available for users to work out if they wish to receive pictures showing reflected light, heat or moisture content. Cloud and temperature information are received direct at Lannion in Brittany and Bracknell in Berkshire, with Jersey Met, receiving it directly by separate landlines from both stations. Unlike Landsat, SPOT and ERS-1, Meteosat images can be received live from the satellite using only a small dish antenna and receiver such as the one at the Teacher's Centre in St. Helier. Finally on the other 26p stamp , the last view further away from Earth is of Olympus. ESA's high-powered Direct Broadcasting Satellite (DBS), Olympus, and launched in 1989, was built by a consortium of European companies, led by British Aerospace as prime contractor. Olympus carries four experimental communications and broadcast payloads. The Direct Broadcast Payload has two hi29/08/06 and the other for European use, which will allow signals to be received using very small dishes. The Specialised Services Payload has a multi-beam antenna, providing five steerable spot beams and channel switching in the repeater to allow a variety of links to be established; the payload is primarily intended to provide specialised services for business use, e.g. video-conferencing, and for television distribution. The Communications payload operates in the 20/30 GHz band that will in the future be used for communication services - present systems operate at 4/6 GHz or around 12 GHz. This payload is being used for experimental video- conferencing, tele-education, data and video transmissions. Finally the Propagation Payload allows experimenters to study the effects of the Earth's atmosphere on radio waves at 20 and 30 GHz. A very wide range of experimenters is presently using Olympus. For example, a school in Devon is experimenting to promote tourism by being linked via satellite with schools in Spain. With the imminent arrival of digital audio tape recorders, it should be possible to download books, magazines or newspapers on to tape for reading at home using the normal television set. We wish to thank Julia McMorrow, BSc, HSc, and Alan Webb, MA, Ceng , MIEE, who assisted in preparing this article for The Jersey Philatelic Bureau, and thanks to the Jersey Philatelic Bureau, for allowing us to reproduce the article.
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