SATELLITE INSTALLATION IN

ORBIT

-By Swapnil Bangera

Satellite Orbits 160km < LEO : Low Earth Orbit < 2000km 2000km < MEO : Medium Earth Orbit < 35,786km GEO : Geostationary Orbit = 35,786km HEO : Highly Elliptical Orbit > 35,786km (Apogee)

Height of Satellite Height of satellite ranges from 160km to

35,786km above the Earth’s surface. For an HEO satellite the apogee height

goes beyond 35,786km.

Problem in Direct Launching of Satellite in its Orbit To launch a satellite

directly into the orbit will require a lot of energy & hence a lot of fuel will be consumed.

Large amount of fuel will result in increase in the weight of launching vehicle and hence use of more fuel.

Direct Launching of Satellite into Orbit

More Energy

More Fuel

More Weight

Types of Satellite Launching ELV : Expendable Launch Vehicle RLV : Reusable Launch Vehicle

Expendable Launch Vehicle ELV launchers put the satellite in an

inclined elliptical orbit called as transfer orbit. The apogee of this orbit is at altitude of about 42164km & perigee is 185 to 370km.

The ELV works in stages and first stage is to place the satellite in an elliptical transfer 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.

PerigeeApogee

Transfer Orbit

Geostationary Orbit

Launch

Reusable Launch Vehicle Example of this type of vehicle is Space

Transportation System (STS) or Space Shuttle.

In this type of launching the part of the 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 low Earth circular parking orbit at an altitude of around 3000km. This allows space check and repair of satellite before actual launch in orbit and 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 transfer orbit which is tangential to the parking orbit and transfer orbit’s apogee coincides with the final orbit which is at 42,164km.

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.

ApogeePerigee Low EarthParking Orbit

Transfer Orbit

GeostationaryOrbit

Thank You!