Satellite communication - Launch
Satellite communication tutorial
Satellite Communication - Launch
Satellites stay in space for most of their lives. We know that the environment of weightlessness is present in space. That’s why satellites don’t need additional powerful frames in space. But, these are needed during the launch process. Because in this process, the satellite trembles violently, until the satellite is placed in a suitable orbit.
The satellite design must be compatible with one or more launchers in order to be able to place the satellite in orbit.
We know that the period of revolution will be longer for a higher apogee altitude according to Kepler's second law. The geostationary transfer orbit period is almost 16 hours. If the perigee is brought to GEO altitude (approximately 36,000 km), then the revolution period will increase to24 hours.
The process of placing the satellite in an appropriate orbit is called the launch process . During this process, from earth stations, we can control the operation of the satellite. Mainly there are four steps to launch a satellite.
First stage - The first stage of the launcher contains rockets and fuel to lift the satellite with the launcher from the ground .
Second stage - The second stage of the launcher contains smaller rockets. These are turned on after the completion of the first stage. They have their own fuel tanks to send the satellite into space.
Third stage - The third (upper) stage of the launcher is connected to the satellite fairing. This fairing is a l shield, which contains the satellite and it protects the satellite.
Fourth stage - The satellite is separated from the upper launch vehicle stage, when it has been reached out of the Earth's atmosphere. Then the satellite will go into a "transfer orbit". This orbit is the satellite higher in space.
When the satellite reaches the desired height of orbit, its subsystems like solar panels and communication antennas are deployed. Then the satellite takes its position in orbit with other satellites. The satellite is now ready to provide services to the public.
Satellite launch vehicles
Satellite launchers launch satellites into a particular orbit depending on the requirement. Satellite launchers are just multi-stage rockets. Here are the two types of satellite launchers.
- Expandable Launch Vehicles (ELVs)
- Launch VehiclesReusable (RLV)
Exhaustible Launch Vehicles
Exhaustable Launchers (ELV) are destroyed after leaving satellites in space. The following image shows what an ELV looks like.
The VLE has three stages. The first and second stages of The ELV will raise the satellite to about 50 miles and 100 miles. The third stage of the ELV places the satellite in transfer orbit. The ELV task will be completed and its spare parts will be fallen to earth, when the satellite reaches orbit.
Reusable launch vehicles
Reusable launchers (RLVs) can be used multiple times for launch satellites. Usually, this type of launchers will return to Earth after leaving the satellite in space.
The following image shows a reusable launcher. It is also known as space shuttle .
The functions of the space shuttle are similar to the functions of the first and second stages of the ELV . The satellite as well as the third stage of the space shuttle are mounted in the cargo hold. It is ejected from the cargo hold when the space shuttle reaches an altitude of 150 to 200 miles.
Next, the third stage of the space shuttle is fired and places the satellite in a transfer orbit. After that, the space shuttle will return to Earth for reuse .