Earlier outer space was the stuff of science fiction novels -today, about 800 artificial satellites are orbiting in space. These are specially designed flying machines, which encircle the Earth or the moon in fixed orbits. Numerous scientific probes were sent into space by various countries, and, since its establishment, the ISS has continued to enrich our knowledge of the endless universe and to open up possibilities of putting it to use. But our increasing activities in space have given rise to a new and serious problem: the accumulation of space debris.
How are satellites launched?
Satellites are transported to space by carrier rockets. During the launch, the satellites mostly have a covering of metal, which protects them against wind, light, dust, air pressure, and the heat resulting from the friction they experience while passing at high speed through the atmosphere. This cover is discarded later on during the journey. During a satellite launch, the thrust of the carrier rockets is calculated in such a way that the satellite swing into its allotted position at the correct height and starts orbiting at a predetermined speed around the Earth. A television satellite thus revolves around the Earth once in exactly 24 hours. Solar sails draw energy from sunlight to generate the power needed to operate satellites.
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