This question appears in Mumbai University > Satellite Communication and Network subject

Marks: 10 M

Year: May 2014

The launching of satellites takes place by a specialized space vehicle called as ‘launch vehicle’ which is used to directly inject the satellite in a low altitude orbits upto 200km.

Launch vehicle is classified as:

I. Expendable launch vehicle (ELV)

II. Reusable launch vehicle (RLV)

I. Expendable launch vehicle (ELV)

• ELV launches put the satellite in an inclined elliptical orbit called as transfer orbit. The Apogee of this orbit is at altitude of about 42164 km and Perigee is 185 to 370km.

• The ELV works in stages and first stage is to places the satellite in an elliptical transfer orbit or Hohmann orbit near perigee. This orbit allows adjustments to be made to the satellite before placing it in final orbit.
• The satellite, after undergoing several revolutions in the transfer orbit, is finally placed in a circular orbit around the equator by firing a rocket engine called Apogee kick motor (AKM) at the Apogee of elliptical orbit which coincides with the final orbit. This is the second stage.
• If the launch is carried out at i=0° then it is a geostationary orbit, else in the third stage if satellite is launched at non zero inclination, the jet thrusters are to be fired to get the circular orbit first and then making that circular orbit equatorial to place the satellite in the geostationary orbit.

II. Reusable launch vehicle (RLV)

• Example of this type of vehicle is Space Transportation System (STS) or Space Shuttle. In this type of launching the part of launcher is used for the launch purpose. At each stage a part of fuel is burnt and as a result mass reduces and velocity increases.

• The satellite flies in a lower earth circular parking orbit at an altitude of around 300km. This allows space check out and repair of satellite before actual launch in orbit and also lowers gravitational force during launch.
• A first velocity increment is provided by an additional stage called Pay Assist Module (PAM) or Perigee Kick Motor (PKM) which puts the satellite in the transfer orbit which is tangential to the parking orbit and transfer orbit’s apogee coincides with the apogee of the final orbit which is at 42164km.
• A second velocity increment is given by the Apogee Kick Motor (AKM) which injects the satellite from transfer orbit to actual geostationary orbit of satellite in the same way as that of ELV launch.