How are satellites sent into space?

According to the Spectator Earth program sponsored by NASA, Nearly 20,000 objects constantly orbit the Earth. Of these objects, a large proportion consists of satellites, only about a quarter of which are active. Among the debris of old satellites and pieces of other rockets that separated during takeoff. Satellites are indispensable in the communications sector and have enabled many major technical advances. We still need to be able to send them there, hundreds, even thousands of kilometers above our heads.

Launching a satellite into orbit: how to send it into space and at what speed?

To send a satellite into space, you first… Use launcherLike Ariane 5 for France. Ariane 5 Or any other launch rocket will be responsible for bringing the satellite to the desired orbit, but also… Give it speed and momentum necessary for it to follow its path around the Earth. Since there is no longer an atmosphere at this altitude, the satellite is no longer subject to air resistance, but it is still subject to air resistance. gravitational force Which should return it to the surface of the Earth. Therefore, the satellite must be launched into space quickly Sufficient satellite coverage (nearly 28,000 km/h!) to be able to generate centrifugal force to keep it in orbit. Although it obviously doesn't need any push, The satellite is still equipped with small engines Which mainly works to correct its paths and return it to its orbit if necessary.

At what altitude and altitude should a satellite or geostationary satellite be sent around the Earth?

The vast majority of satellites are sent into low orbit, At an altitude of less than 2000 km. They are small satellites designated for the communications sector, such as Iridium (telephony) or… OneWeb (Internet), but also the satellites of the Starlink network designed by Elon Musk or the International Space Station, which are located at a distance “Just” 340 km Above our heads. Some larger observation satellites are sent into medium orbits, Its altitude ranges between 2,000 and 35,000 km : This is the case of the navigation satellites of the GPS and Galileo networks, transmitted between them Altitude 20,200 and 22,000 km. Finally, some satellites are sent to approx Altitude: 36,000 km : They are called geostationary satellites because, in this orbit, they can follow their rotation in a synchronous manner with the planet Earth, as do the Hot Bird satellites, the main network of European television and radio broadcast satellites.

Orbit: How does a satellite communicate with Earth?

At this altitude, everything must be carefully focused for the satellite to do its job. To communicate with the Earth and Send or resend informationThe satellite transmits both Radio waves and microwavesMicrowave signals are generally preferred because they are stronger than radio waves. Its propagation speed is equal to the speed of light. Or 300 thousand kilometers per second. To capture these waves, we still use the good old antenna system today, particularly umbrella antennas that can reach several hundred meters in height.

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