Where do satellites fly?

Answer 1

Man-made satellites are either in low, medium or high earth orbits, depending on their function. The closest ones, including the International space station, are in a low earth orbit, up to a height of 2000 km. The International Space Station orbits at a height of around 340km, while the Hubble Telescope is around 595km. The advantage of these is that less energy is required to get there, but the disadvantage is that their orbits may decay over time, since there is some drag on the atmospheric gas still at these heights - so these may need a 'boost' every now and then to maintain their orbits. At higher altitudes, satellites will orbit more slowly, taking longer to make one orbit. The medium Earth orbit extends to 35,786km above the Earths surface, from here the high earth orbit begins. At this point, the time taken for a satellite to orbit once around the earth is 24 hours, the same as one day. 35,786km is a special orbit for Geo-stationary satellites. Since they orbit the earth in the same time that it takes the earth to spin once on its axis, it means that the satellite can stay in roughly the same spot over the earth.