Various type of Orbits around Earth- Part 1

By Aman|Updated : July 1st, 2021

An orbit is a curved path that an object in space (say spacecraft or a satellite) takes around another object (say earth) due to gravity. This article discusses various types of orbits around earth, their properties and importance. Space technology is an important part of the syllabus of UPSC Prelims.

Table of Content

Various Types of Orbits

  • An orbit is a curved path that an object in space (say spacecraft or a satellite) takes around another object (say earth) due to gravity.
  • Objects of similar mass orbit each other with neither of them at the centre but on the other hand small objects orbit around larger objects.


Launching a satellite into the orbit:

  • A satellite is put into orbit by being placed hundreds or thousands of kilometres above Earth’s surface and then given a ‘push’ by the rocket’s engines to make it start on its orbit as shown in the figure above.
  • If the push is not enough, it will fall back to Earth.
  • If the satellite is not high up enough from the Earth’s surface, it will need tremendous velocity to orbit while the vice-versa is also true, hence it is easier to put satellites into orbit at higher levels.
  • In space, there is no air friction, so gravity lets the satellite orbit around Earth with no further assistance.

Geostationary orbit (GEO)

  • Satellites in geostationary orbit (GEO) orbit the Earth above the equator from west to east following Earth’s rotation, taking 23 hours 56 minutes and 4 seconds by travelling at exactly the same rate as Earth that makes satellites in GEO appear to be ‘stationary’ over a fixed position.
  • In order to match Earth’s rotation, the speed of GEO satellites should be around 3 km per second at an altitude of about 35,786 km.
  • Satellites in GEO cover a large range of Earth so as only three equally-spaced satellites can provide near-global coverage as when a satellite is this far from the Earth, it can cover large sections at once.
  • GEO is used by telecommunication satellites. In this way, an antenna on Earth can be fixed to always stay pointed towards that satellite without moving.
  • It can also be used by weather monitoring satellites as they can continually observe specific areas.


Low Earth orbit (LEO)

  • A low Earth orbit (LEO) is an orbit that is relatively close to Earth’s surface, normally at an altitude of less than 1000 km but could be as low as 160 km above Earth (vs 14 km for aeroplanes)
  • LEO satellites do not have to follow a particular path around the Earth like the GEO at the equator, thus their plane can be tilted.
  • It is the orbit most commonly used for satellite imaging, as being close to the surface allows it to take images of higher resolution.
  • It is also used for the International Space Station, as it is easier to travel to and from it at a shorter distance.
  • Satellites in this orbit have a speed of around 7.8 km per second, which means a satellite takes approximately 90 minutes to circle Earth.
  • Individual LEO satellites are less useful for telecommunication as they move so fast across the sky and require a lot of effort to track from ground stations.
  • So they work as part of a large constellation of multiple satellites to give constant coverage to large areas of the Earth.




Medium Earth orbit (MEO)

  • Medium Earth orbit comprises a range of orbits between LEO and GEO.
  • Like LEO, it also does not need to take specific paths around Earth, and it is used for many different applications.
  • It is very commonly used by navigation satellites from tracking large aeroplanes to getting directions on the smartphone.


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