The Secret World Of Satellites
Satellites are objects that orbit a planet or a star. The earth is a satellite as it orbits the sun, the moon is likewise considered a satellite because it orbits the earth. However, these are natural satellites. Man-made satellites are machines set to orbit the earth. These satellites have different classes according to the types of their orbit, as well as their functions.
According to Function
When we say satellite, the first thing that comes to mind are Astronomy satellites, such as the Hubble Space Telescope. These satellites are really just large telescopes that take pictures of astronomical objects, including distant galaxies, stars, and supernovas. Away from the Earth’s atmosphere, these telescopes can take clearer pictures of the universe around us.
Communication satellites are another commonly known type of satellite. These satellites enable our electronic devices to function, including televisions, phones, and radio. Some lesser known satellites include mining satellites, navigation satellites, reconnaissance satellites, remote sensing satellites, weather satellites, and search and rescue satellites. Mining satellites enable geologists to connect with their headquarters when they are on a project area. Navigation satellites, such as Navstar, enable ships and other marine vessels to navigate the oceans. Reconnaissance satellites are employed by countries to spy on other states. Some examples include Kennan, the Big Bird, and Lacrosse.
Search and Rescue satellites are designed specifically to recognize emergency beacons from ships, planes, and other vessels. One example is the Cospas-Sarsat Search and Rescue system. Weather satellites are employed to monitor weather conditions around the world. They measure radiation, water temperature, the amount of snow, as well as water vapour. Weather satellites can likewise monitor volcanic eruptions, as well as track ash cloud formation and movements. One example of a weather satellite is the Meteosat. Remote Sensing satellites track human resources including mineral deposits, bird migrations, and even rainforest depletion. Lastly, Space Exploration satellites are not technically satellites as they do not orbit a planet or a star. Instead they are designed to explore the universe, similar to the function of a satellite. They are also called space probes. One example of which is NASA’s Galileo.
According to Orbit
There are four types of satellites classified according to their orbits. Low earth orbit satellites are relatively lower and faster than the other satellites. They orbit the earth at a speed of 90 minutes per one complete orbit. Most low earth orbits are military reconnaissance satellites. They are very short-lived, mostly just lasting a few weeks at a time.
Sun-synchronous orbit satellites are designed to be at a fixed position relative to the sun for the whole year. This position enables them to make accurate weather predictions. Thus, almost all weather satellites are placed in a helio-synchronous orbit. Geosynchronous or Earth-synchronous orbit satellites are those that match the Earth’s rotation exactly, taking 24 hours to make one complete rotation.
However, unlike other satellites, these do not orbit the earth on the equatorial plane. Instead, they occupy the higher latitudes, called the Molniya orbits. Russian and Canadian communication satellites can be found there. Lastly, geostationary orbit satellites take up the majority of communication satellites. Compared to the geo-synchronous orbit satellites, they occupy the equatorial plane, and also take 24 hours to make a full rotation. They are called geostationary because they have a fixed position on the equator of the earth.