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What is a satellite ?
A satellite is basically a self-contained communications system with the ability to receive signals from Earth and retransmit those signals back with the use of a transponder— an integrated receiver and transmitter of radio signals. A satellite has to withstand the shock of being accelerated during launch up to the orbital velocity of 28,100 km (17,500 miles) an hour and a hostile space environment where it can be subject to radiation and extreme temperatures for its projected operational life, which can last up to 20 years. In addition, satellites have to be light, as the cost of launching a satellite is quite expensive and based on weight. To meet these challenges, satellites must be small and made of lightweight and durable materials. They must operate at very high reliability of more than 99.9 percent in the vacuum of space with no prospect of maintenance or repair.
How Do Satellites Orbit Earth?
Most satellites are launched into space on rockets. A satellite orbits Earth when its speed is balanced by the pull of Earth's gravity. Without this balance, the satellite would fly in a straight line off into space or fall back to Earth. Satellites orbit Earth at different heights, different speeds and along different paths. The two most common types of orbit are "geostationary" and "polar."
A geostationary satellite travels from west to east over the equator. It moves in the same direction and at the same rate Earth is spinning. From Earth, a geostationary satellite looks like it is standing still since it is always above the same location.
Polar-orbiting satellites travel in a north-south direction from pole to pole. As Earth spins underneath, these satellites can scan the entire globe, one strip at a time.
The Purposes Of Satellites
- Navigation satellites are used for communications and position identification.
- Weather satellites use sensors to monitor the Earth's weather systems and patterns. They measure visible light, reflected light, and infrared radiation.
- Voice and data communications. Wi-Fi networks, internet service providers, and emergency communications services use them.
- Broadcasting applications, including sending radio and television signals to consumers.
- The International Space Station is a satellite that provides many services, including research and development, and Earth and space observation among other applications.
- Banking and Insurance - Connectivity can provide remote offices, ATMs and insurance companies with scalable infrastructure that grows with their client base and ensure business continuity.
- Civil Services - Satellites can connect schools, universities, administrations, public entities, hospitals, and more, with efficient, highly reliable, point-tomultipoint networks that can provide connectivity in even the harshest environments.
- Safety - Earth observation satellites can monitor ocean and wind currents and the extent of forest fires, oil spills, and airborne pollution; this information helps organize emergency responders and environmental cleanup.