Satellites are present in our daily life in ways we can hardly imagine. Through them we are able to know the weather forecast, to watch in real time a soccer match anywhere in the world, or to make use of navigation apps such as Google Maps, that is, through satellites we have practicality and instantaneity in our hands, and not often do we have the dimension of that.
A satellite is any body in orbit around the Earth or another celestial body. Thus, the moon is a satellite, yet a natural one. Now satellites created by human beings are known as artificial satellites and are present in various segments such as communications, observation of the Earth, science, meteorology, technological development, navigation, defense, space exploration, and manned flight.
63 years ago, the first satellite, called Sputnik, was launched; its mission was to analyse the upper layers of the atmosphere, besides studying conditions for launching essential cargoes to space. According to the Brazilian Space Agency (AEB), after the historic launching of Sputnik, over six decades more than 9.5 thousand satellites have already been shot into space, which represents an average of 3 satellites launched per week. Nearly 2.4 thousand of those are still in operation, and 55 are used for scientific ends.
On February 28th, 2021, the Brazilian satellite known as Amazon-1 was launched into orbit. The launching took place in India and lasted around 18 minutes. According to the National Institute of Space Researches (INPE), it is the first satellite for observation of the Earth totally planned, integrated, tested, and operated by Brazil. Its equipment is coordinated by Inpe and its objective is to monitor agriculture, water reservoirs, and deforestation in the Brazilian territory, particularly in the Amazonian region.
Its mission shall last four years, at the end of which period evaluations will be made in order to analyse the viability of keeping the satellite a while longer. If the mission is terminated, Brazil still has a 25-year term to eliminate the satellite in orbit. Besides having environmental ends, Amazon-1 shall provide technological actions operations for Brazil.
One of the main environmental problematics in Brazil is related to deforestation; for that reason there has been, since 2004, a tool of alert - the DETER (Deforestation Detection in Real Time) - for control and monitoring of deforestation which employs data with a spatial resolution of 250 meters from a MODIS - Moderate Resolution Imaging Spectroradiomer equipment aboard the Terra and Aqua satellites of the United States.
Communication satellites are an essential means of transmission since communication in distant zones lacking ground telecommunications infrastructure would not be possible without the use of satellites. It is through satellites that it is possible to provide communication services for:
* Locations devastated by a natural disaster, such as a hurricane;
* People in traffic on airplanes and boats;
* Events in isolated areas, such as a rally or skiing competition, or practitioners of extreme sports, such as mountaineering;
* Rural areas;
* Enterprises acting in remote places, such as aeolian power plants or mining.
Communication satellites correspond to more than half of the satellites in the orbit of the Earth, and they are the ones that fulfill the distribution of telephone, television, and internet signals.
Satellite navigation systems are able to define the geospatial positioning of an object in space by employing artificial satellites which orbit around the planet. GPS is an example of a satellite navigation system developed by the United States during the 1970s and for many years has been the only alternative for supplying geographic positions around the Earth. Nowadays, however, it is not the only existing system, Glonass and Galileo being either examples of solutions from other countries.
GPS has the basic function of rendering information on the position of a determinate equipment which is able to receive the signals emitted by it. Today, GPS is the best satellite navigation system functioning. However, in a few years, it is likely to cease to be a unanimity, since new mechanisms have more resources to offer, such as the possibility of making calls for help in case of emergency and providing higher precision of localization for the user.
With the pandemic, new technologies appeared, such as applications that might help in the struggle against the coronavirus. Through satellite images, it is possible to follow the traffic of a population in determinate areas and so have knowledge of whether rules of social isolation are being respected or not. Besides the monitoring referent to measures of social isolation, it is possible to follow construction activities of structures destined to combat the disease, such as hospitals or roadblocks.
Meteorological satellites are employed to monitor the weather and climate of the Earth, as well as cloud formations, forest fires, pollution effects, auroras, and dust and lightning storms. There are some meteorological satellites that operate by infrared radiation and do not need sunlight for their functioning.
Information obtained by meteorological satellites can be used to make temperature graphs of the sea surface, whose data are not only useful for the climate, but also for fishing and navigation. The meteorological system is the only one able to reach a total coverage of the temperature of the atmosphere and distinct heights.