How do Satellites Work?

Satellite perform many types of work at the same time. The instruments fitted with the satellites, help them execute all the functions systematically. To know how satellites work, read on...

Satellites are physical objects that are developed by humans and placed in Earth's orbit. They are commonly used for various scientific and technological purposes. Satellites have a number of instruments and subsystems to accomplish its mission. Basically, a subsystem is a set of devices that are responsible for carrying out the operations of the satellite, without any interruptions. The subsystems that are an integral part of any satellite, are described below:

Communications Subsystem

The communication subsystem is the most vital part of a satellite. The key components of a communication subsystem are - antennas, receivers and transmitters. Their main function is to receive and send signals all across the globe. Some satellites and ground stations have specially designed radio dishes that are used for exchange of data. The curved section of these dishes helps in the reflection of both incoming as well as outgoing signals, from its central horn. The antennas are needed for the purpose of transmission of pictures at different frequency levels and with varying coverage. They are also capable of receiving instructions from Earth. The beacons and transponders fitted in some satellites, help in ground tracking.

Command and Data Handling Subsystem

This subsystem comprises computers that collect all the data and process them on board. These computers are capable of delivering results according to the instructions received from the Earth. They are used for the physical measurement of distant objects. The inputs for this purpose are received from various sensory devices and processed to convert them into encoded data and the same is transmitted to the ground station for further analysis. This type of data transmission is a crucial task of satellites.

Power Supply Subsystem

The work of satellites is completely disrupted without the power supply subsystem. The main task of the power supply subsystem is to generate, store and supply adequate amounts of electrical power for the satellite. The power requirements depends on the total area covered by the satellite, kinds of instruments used and communication load.

There are various modes of power supply used by satellites. They can use chemical batteries, solar cells or radioisotope devices. Solar cells are the most widely used in the power supply subsystem of satellites. Solar cells convert the solar energy into electrical energy. They are therefore the most reliable source of power supply. Chemical batteries oxidize the fuel for the production of power. They are used to supply electricity, when the satellite enters the shadow of the Earth. The disadvantage of batteries is their bulky size. For this reason, they are used mostly for short-term missions.

Some of the power supply subsystems are also provided with turbogenerators or thermionic generators. These generators use heat energy for producing electricity. The heat energy required is either obtained from the sun or from small nuclear reactors fitted with the subsystem. However, nuclear reactors have been used in satellites only on an experimental basis.

A satellite can work only when all these subsystems are performing their functions correctly. Malfunction in any of these subsystems can lead to total breakdown of the satellite.

By Bidisha Mukherjee
Last Updated: 9/27/2011

Ads by Google

Renewable Energy Kit   Solar, Wind, Fuel Cells. All in one with extensive curriculum  www.heliocentris.com

Intelligent Telemetry   Telemetry for control of mission critical assets  www.controllis.com

SpecTIR   Hyperspectral remote sensing data collection and analysis  www.spectir.com

Lightem CWDM DWDM Optics   1-10G Transceiver SFP XFP X2 Xenpak Wavelengths Converter Transponders  www.lightemsystems.com

Communication Antennas   Smart Metering Antennas GPS Antennas  www.mobilemark.com

Cat Gas Generator Sets   Natural And Biogas Fueled Power Ranges from 100kW to 6M  www.catelectricpowerinfo.com/Gas

China Sunergy manufacture   Solar Cell manufacturers in China High quality with good service.  www.chinasunergy.com