Mechanism of Launching a Satellite
Theoretically a satellite could be placed into geosynchronous orbit in one step but practically it is a two or three step process. The placement of satellite in the geostationary orbit is carried on the principle of Hohmann Transfer. This post includes explanation of three commonly used satellite launching mechanism that are employed and used by Space Transport System (STS), Expandable Launch Vehicle (ELV) and Special Expandable Launch Vehicle (SELV) in detail. Launching a satellite into orbit is a process which is described by the authorities.
Generally there are three techniques that are employed as the mechanism of launching a satellite.
Technique First :
In the first technique, first the satellite is placed in lower circular earth orbit at an altitude of around 300 Km. Then a velocity increment is required and it is carried out by various auxiliary propulsion stages. One velocity increment changes the satellite lower circular earth orbit into an elliptical orbit with a perigee of about 300 Km and apogee at 42164.2 Km (radius of geosynchronous orbit) Then in this case second velocity increment is required and it finally places the satellite into the desired orbit. Space Transport system (STS) follows this techniques.
Second Technique :
The second technique has been used by expendable launches vehicles such as Ariane, Delta or Atlas-centaur launcher. In this case there is no initial circular orbit and the vehicle provides the necessary velocity at the perigee of the elliptical transfer orbit. Thus here only one velocity factor increment has been observed from the satellite at the apogee part.
Third Technique :
The third technique has been used by the Special Expendable Launch Vehicle such as US Titan III C and the USSR Proton launchers. In this case satellites are directly placed into geostationary orbit.
The satellite velocity at the apogee and perigee can be calculated as given below:
Vs2 = (2µ/r) – (µ/a)
- µ = Gravitational constant
- A = Semi- major axis
- R = Distance from the center of the Earth to the point where velocity is required.
Above are the three most important techniques that are employed as the Satellite launching Mechanism.
- Satellite Communication System
- Methods of Satellite Stabilization
- Analog and Digital Communication
- Advantage and Disadvantage of Satellite Communication
- Satellite Subsystems in Satellite Communication Systems
Reader can share their views or feedback with us through comment, in the below comment box for further improvement.