Earth observation satellites constantly supply data from all parts of the world, and their resolution is continually increasing. They are used for such purposes as mapping forest fires, ocean ice fields, natural disasters, and oil spills, where time is a critical factor.
The vision for the future anticipates “live” data transmission following the example of communication satellites. Geostationary relay satellites in permanent visual contact with earth observation satellites take over their data. A network of relay satellites then passes on these data around the world at the speed of light to ground stations, for example in Oberpfaffenhofen.
Today, these data sometimes require several hours or even days to reach their users. The reason? The data can only be delivered when the earth observation satellite is in direct visual contact with a ground station. Until then, the data have to be stored on board the satellite. If the satellite’s storage capacity is too low, the data may have to be transferred to very remote ground stations which lack a link to the worldwide high speed network.
New transmission approaches are urgently required because of the enormous amounts of earth observation data being collected, and these can now be tested with EOC’s new antenna. It will serve in the future as a bridgehead to the geostationary relay satellite AlphaSAT. This communication satellite is to be launched in summer 2013 and for the first time will be capable of optical reception of earth observation data transmitted to it via lasers. Enormous amounts of data can be transferred through space in the shortest possible time with the help of lasers. However, subsequent transfer to a ground station will be handled via microwave transmission. In contrast to lasers, microwaves are hardly disturbed by Earth’s atmosphere and make possible smooth reception of data independent of weather conditions. The newly installed antenna uses the Ka-band at a frequency of 26 gigahertz.