Satellites launched by SSLV in ‘wrong orbit, not usable’
For Prelims
About Small Satellite Launch Vehicle (SSLV):
- SSLV is capable of carrying satellites which weigh less than or equal to 500 kg only.
- The vehicle is used to launch satellites to Low Earth Orbit (LEO).
- SSLV is ISRO’s lightest launch vehicle, weighing around 110 tons.
- It is a three-stage launch vehicle which uses solid fuel in all its stages.
Different types of Orbits
- Orbits are classified into three i.e., High Earth orbit, Medium Earth orbit, and Low Earth orbit.
High Earth orbit:
- It is the farthest away from Earth at about 35,000 km. Weather satellites and some of the communication satellites are placed in this orbit.
Geosynchronous Orbit:
- A special High Earth Orbit when a satellite reaches exactly 42,164 kilometers from the center of the Earth, in which its orbit matches Earth’s rotation.
- The satellite seems to stay in place over a single longitude, though it may drift north to south.
Geostationary Orbit (GEO):
- A satellite in a circular geosynchronous orbit directly over the equator will have a geostationary orbit i.e., it does not move at all relative to the ground. It is always directly over the same place on the Earth’s surface.
- A geostationary orbit is extremely valuable for weather monitoring because satellites in this orbit provide a constant view of the same surface area.
- Because geostationary satellites are always over a single location, they can also be useful for communication (phones, television, radio).
- India’s navigational satellite constellation IRNSS has satellites in both Geostationary and Geosynchronous orbits
Medium Earth Orbit (MEO):
- Medium Earth orbit is any of the orbits anywhere between LEO and GEO. It is very commonly used by navigation satellites like GPS and Europe’s Galileo systems.
- MEO satellites do not have to track the path along the earth’s equator.
Low Earth Orbit (LEO):
- It is normally at an altitude of less than 1000 km but could be as low as 160 km above Earth.
- LEO satellites do not always have to follow a particular path around Earth and can follow a tilted plane.
- This allows satellites to have more available routes in LEO, which is one of the reasons why LEO is a very commonly used orbit.
- It is the orbit most commonly used for satellite imaging, as being near the surface allows it to take images of higher resolution.
- The International Space Station (ISS) also follows this orbit, which allows for easier movement of people.
Polar orbit and Sun-synchronous orbit (SSO):
- Satellites in polar orbits travel around the Earth from north to south rather than from west to east, nearly passing over Earth’s poles.
- Satellites in SSO, travelling over the polar regions, are synchronous with the Sun.
- This means they are synchronised to always be in the same ‘fixed’ position relative to the Sun.
- A satellite in a Sun-synchronous orbit would usually be at an altitude of between 600 to 800 km.
Source The Hindu
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