Ioonos

HOW DOES IT WORK?

Earth sends a signal to a satellite (for example, a TV programme), which amplifies it and sends it to another point on Earth, that is, to other television viewers. That way, billions of people can see, with only the smallest time difference, the final of the World Cup. With satellites there are no more problems of mountainous areas or data speeds (undersea cables) or breakdowns due to snow, wind or earthquakes…. Their only shortcomings? They are expensive and it takes time for the signal to cover the 72,000 km of the Earth-satellite return journey: about 0.2 of a second…

Why not put them lower?

We’ve tried. The first communications satellites (Echo 1, built by NASA, was the pioneer in 1960) were put into orbit" >low orbit. But communications were regularly cut, because on account of their orbit the satellites were turning several times a day around the Earth. So geosynchronous* orbits are used heavily since satellites there turn at exactly at the same time as the earth, ensuring continuous communications… Useful for goals, isn’t it?

Constellations of satellites

Complete networks of satellites have been created. They work together to service the largest number of people possible. They can be international, like Intelsat*, the international organisation of communications satellites, which brings together 120 countries, or Inmarsat (the International Maritime Satellite), or regional (the European Communication Satellite in particular, which in Europe formalises the cooperation of its member States). Especially, with the explosion in demand, we are coming back to communications satellites on medium-earth orbits (MEO*), which create amongst themselves constellations, sorts of spider webs whereby one can compensate the others for what they lose when they go over the side of the Earth.