Satellites and Sputnik

Satellite is any object that orbits or revolves around another object. For example, the Moon is a satellite of Earth, and Earth is a satellite of the Sun. The man-made satellites that orbit Earth and the Sun -- highly specialized tools that do thousands of tasks every day. Each of these satellites has many parts, but two parts common to all satellites are called the payload and the bus.

The payload is all the equipment a satellite needs to do its job. This can include antennas, cameras, radar, and electronics. The payload is different for every satellite. For example, the payload for a weather satellite includes cameras to take pictures of cloud formations, while the payload for a communications satellite includes large antennas to transmit TV or telephone signals to Earth.

The bus is the part of the satellite that carries the payload and all its equipment into space. It holds all the satellite's parts together and provides electrical power,computers, and propulsion to the spacecraft.

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English: A replica of Sputnik 1, the first artific...

English: Satellites in Earth orbit. Solar Galaxy �...

The bus also contains equipment that allows the satellite to communicate with Earth.

A satellite's orbit depends on its task, speed, and distance from Earth. Following are the main orbit types of satellites: -

LEO (Low Earth Orbit)

Polar

GEO (Geosychonous Equatorial Orbit)

Elliptical

Communications satellites act as relay stations in space. People use them to bounce messages from one part of the world to another. These messages can be telephone calls, TV pictures, or even Internet connections like the one you're using now.

Communications satellites like EchoStar are in geosynchronous orbit (from geo = Earth + synchronous = moving at the same rate). That means that the satellite always stays over one spot on Earth. The area on Earth that it can "see" is called the satellite's "footprint." Here is one footprint...