Describe how an artificial satellite using
two stage rocket is launched in an orbit
around the earth. Explain the nature of all
the possible orbits of a satellite
Answers
Answer:
All satellites get into orbit by riding on a rocket. For most satellite launches, scheduled launch rocket is aimed straight at first.
This gets the rocket through the thickest part of atmosphere most quickly and minimizes the fuel consumption.
After passing through a long distance through atmosphere, rocket control mechanism uses the inertial guidance system
to calculate necessary adjustments to the rocket nozzle to tilt rocket to the course described in the flight plan.
In the flight plan, launch vechicle is headed to east because earth rotates to east. Also in flight plan,
launch vechicle is boosted by burning fuel to match the launch vechicle's movement with earth rotational speed.
Once the rocket reaches extremely thin air at about 200 km up, rockets navigational system fires small rockets to turn
the launch vechicl into horizontal position. Satellite is then released into space.
The aim of satellite launching is to take away the satellite from earth, put the satellite into proper orbit and
give th required orbit velocity so that satellite balances between gravitational pull and
the inertia of satellite motion i.e., satellite tendency to keep going. At an altitude of 240 km, this orbit velocity is about 28000 km/hr.
At the correct orbital velocity, gravity exactly balances the satellite, pulling down towards earth's centre just enough
to keep the path of satellite curving like earth's curved surface. Higher the orbit, longer the satellite can stay in orbit.
At lower orbits, satellite run into traces of earth;s atmosphere, which creates drag.
Drag causes the orbit to decay until satellite falls back into the atmosphere and burns up.
At higher altitude, where the vacuum of space is nearly complete, there is no drag and satellie stay in orbit for ever.
Satellites are classified based on their height above earth's surface. There are three categories.
1. Low earth Orbits (LEO)
LEO satellites occupy a region of space from about 180 km to 2000 km above earth.
They are ideal for making observation, for military purposes and for collecting weather data.
2. Geosynchronous orbits (GEO)
GEO satellite orbits are at an altitude greater than 36000 km and their orbit period is same as earth;s rotation period, i.e., 24 hours.
Several hundred TV, communication and weather satellites all uses GEO orbits
3. Medium Earth Orbits (MEO)
These satellites park in between low and high fliers, i.e., they occupy a region between 2000 km and 36000 km above earth.
Navigation satellites used for GPS work well at this altitude.
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