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Sunday, February 4, 2018

What is Satellite?

What is Satellite:

     A satellite is a artificial or man made object injected into space for particular applications. (Applications such as weather monitoring, astronomical observation, resource satellites, space explorations..,). The satellite is injected at a certain height from the earth surface which we call orbit. Man-made satellites are also called artificial satellites, this is because to distinguish from natural satellite (Earth's Moon).

Satellite orbiting Earth

What is difference between natural and artificial satellite?

Natural Satellite : A natural satellite is a astronomical object orbiting around particular planet. Example: The Moon which orbits around our earth is.

Artificial Satellite:  Artificial satellite is a human made object commanded or programmed to orbit around any astronomical object. Example: Mangalyaan Satellite around planet Mars and Chandrayaan-1 around Moon.

First Satellites of Nations in 20th Century:
  1. Sputnik-1              Soviet Union
  2. Explorer-1             United States
  3. Asterix                   France
  4. Osumi                    Japan
  5. Dong Fang Hong  China
  6. Prospero                United Kingdom
  7. Rohini                    India
  8. Ofeq-1                    Israel
  9. Kosmos 2175         Russia
  10. Strela                     Ukraine
First Satellites of Nations after 20th Century:
  1. Omid                                           Iran
  2. Kwangmyongsong 3 Unit-2      North Korea
  3. Dove Pioneer, Lemur-2 (X2)     New Zealand
Types of Artificial Satellite:
  • Earth observation satellites
  • Navigational satellites
  • Communication satellites
  • Astronomical satellites
  • Biosatellites
  • Killer Satellites
  • Crewed satellites (Spaceships)
  • Nanosatellites
  • Recovery satellites
  • Reconnaissance satellites
  • Weather satellites
  • Deep space satellites
  • Tether satellites
  • Space stations
Satellite Subsystem:
    • Structural system
    • Telemetry system
    • Power system
    • Thermal control system
    • Attitude control system
    • Payloads
    • Thruster control system
Origin of artificial satellites:

     In history of science, great scientist Sir.Issac Newton first published a paper on "Possibility of an artificial satellite". Similarly, in 1879 Edward Everett Hale depicted a satellite in his frictional writing. Later in 1903 Konstantin Tsiolkovsky mentioned satellite in his published paper "Exploring Space Using Jet Propulsion Devices"

Sputnik-1 First satellite in space 1957

     The space exploration began with the first successful launch of Sputnik-1 satellite of Soviet Union in 1957. It operated for 21 days in orbit and it's mission life ended in 26th October 1957. After the successful launch of Sputnik-1, many country started to launch their own satellites into space. Some of the first satellites of the nations are mentioned above.

Frequently asked questions:

How many satellites have been launched since launch of earth's first satellite?

     As per 2013 estimate by "Global experts Agree Action Needed on Space Debris" European Space Agency, more than 6,600 satellites from 40 countries around world have been launched. Out of these 6,600 only 1000 satellites were in operational.

Which is the oldest satellite in space?

     According to the statement of Wikipedia, Vanguard-1 is the oldest satellite in space, which is still orbiting the earth with its rocket's upper stage. It deactivated in 1964.

How many satellites are currently in active?

     As listed by Goddard Space Flight Center there are 2,271 satellites are currently active in orbit. Of these 1,324 satellites were from Soviet Russia and 658 satellites from United States of America.

Can we see satellites from Earth?

     Yes, we can see satellites from earth in the night sky when they pass overhead at a particular height. It can be seen at a place where there is no light and cloud free sky. It will look like a star moving across the sky. (Note: blinking of moving light is not star but a plane)

Which country has most satellites in space?

     Russia has 1,324 satellites, United States has 658 satellites, China has 177 satellites and Japan has 56 satellites. (Source: World Atlas)

How many satellites are owned by Google?

     As far 13 satellites are owned by Google and they are called GeoEye Satellites.

How much does it cost to built and launch a satellite?

     To built a satellite, it costs from $50 dollars to $500 million dollars. For launching it costs about $8000 dollars. (approximately)


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