How do satellites work?
How do satellites stay in orbit?
Satellites are bodies that orbit round the Earth. They are put in to an orbit by powerful rockets. Just like the Moon, they are all kept in orbit by the gravitational pull of the Earth.
In order to stay in orbit at a certain altitude (height) , the satellite must maintain the right speed to balance the pull of gravity. Lower the altitude of the satellite faster it would have to travel to stay up. Those satellites which are high in the orbit travel at slower speeds, but take longer to complete 1 orbit of the Earth.
Although satellites travel very fast, some of them seem to be standing in one place, when viewed from the ground! This happens when a satellite is put into an orbit at just the right altitude (36,000 Km above equator) and speed so that it takes 24 hours to circle round the Earth once. This is the same time as the Earth, hence the satellite appears to float over one point. See below. These type of satellites are known to have a GEO-STATIONARY or SYNCHRONOUS orbit.
Satellites are bodies that orbit round the Earth. They are put in to an orbit by powerful rockets. Just like the Moon, they are all kept in orbit by the gravitational pull of the Earth.
In order to stay in orbit at a certain altitude (height) , the satellite must maintain the right speed to balance the pull of gravity. Lower the altitude of the satellite faster it would have to travel to stay up. Those satellites which are high in the orbit travel at slower speeds, but take longer to complete 1 orbit of the Earth.
Although satellites travel very fast, some of them seem to be standing in one place, when viewed from the ground! This happens when a satellite is put into an orbit at just the right altitude (36,000 Km above equator) and speed so that it takes 24 hours to circle round the Earth once. This is the same time as the Earth, hence the satellite appears to float over one point. See below. These type of satellites are known to have a GEO-STATIONARY or SYNCHRONOUS orbit.
If an object is fired at 8Km/s, 25 times the speed of sound, then it would still fall towards Earth, but it would stay the same height above the earth's surface, because of the curving of the Earth. This then becomes a satellite, in orbit around the Earth.
Satellite orbits
Satellites can be launched into 2 kinds of orbits, 'Polar' and 'Equatorial'. See animation below:
Satellites can be launched into 2 kinds of orbits, 'Polar' and 'Equatorial'. See animation below:
Artificial Satellites image courtesy of science-resources.co.uk
Polar Orbit:
These type usually have fast speeds, lower orbits. They travel from north to south around one side of the Earth and then back north round the other side. They pass over different parts of the Earth as the Earth turns on its axis. The result is that the satellite appears to travel a spiral path over the Earth's surface.
Equatorial Orbit:
In this case the satellites travel eastwards in an orbit directly above the equator. These type of satellites usually have moderate speeds and high orbits, altitude of around 36,000 Km. At this height they take one day to make one complete orbit. However, the Earth is spinning beneath the satellites in the same direction and as a result each satellite appears to remain in one place above a point on the equator.
The entire Earth can be covered by just 3 geo-stationary satellites. See animation on below:
Geo Stationary Satellites image courtesy of science-resources.co.uk
If you 'ring' Australia, a microwave radio signal is transmitted from a 'dish' aerial up to the satellite. In turn the satellite transmits it down to another dish aerial in Australia (see animation below). Microwaves are used since they travel in a straight line, and pass easily through the Earth's atmosphere. See animation below:
Radio Waves image courtesy of science-resources.co.uk
Similarly, television satellites can broadcast programmes to whole continents, for example all of Europe. To view programmes, you need a satellite dish to pick up the signal. See animation below:
TV Satellite image courtesy of science-resources.co.uk
There are 4 main types of satellite
Monitoring the Weather - they take photographs of the weather, and send the picture back to Earth by radio signals.
Observing and Exploring the Earth - very useful for land survey. These are lower satellites that take photographs in very fine detail. These are very important in spotting forest fires, pollution, crude oil deposits and the health of crops.
Communication and Navigation - Military use these for spying. These are also used to guide ships and planes on their journey.
Exploring the Solar System and Universe - These type of satellites are equipped with telescopes. They can take very detailed pictures of planets, because they are away from the Earth's atmosphere.
Hubble Telescope image courtesy of science-resources.co.uk
Tags: How do satellites work; types of satellite; artificial satellites; TV satellites; hubble telescope, radio waves; geo stationary satellites
