People used to learn how to navigate by reading their surroundings back in the day. For instance, the stars. This is why we came up with names like the North Star (Polaris), which would always point north. We still use constellations to help us navigate in the modern period, but they wouldn’t be made of stars in the sky. Believe it or not, we are pretty familiar with what we refer to as satellite constellations.
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GPS
The invention of the Global Positioning System (GPS) may be traced to the start of the Space Race in the 1950s when the beeping broadcasts of the artificial satellite Sputnik 1 were monitored to establish its location in orbit. The Earth’s gravitational and magnetic fields and other prevalent phenomena gave orbital positioning systems developed in the decade that followed room for mistake.
As a result, the United States began developing Navstar, the GPS’s immediate forerunner. Over time, the system’s early military uses gave way to civil, commercial, and scientific ones. That would be the rationale behind including GPS in commonplace items like cars and phones.
This system’s space section would consist of a nominal constellation of 24 satellites that would be operational 95% of the time. As of June 2022, 31 satellites were actively being used, making up a more significant number. The ephemeris (tabular statement of trajectory) is updated every two hours.
GLONASS
The GPS’s predecessor, the Global Navigation Satellite System (GLONASS), was also influenced by the potential of radio-astronomy technologies for navigation. In 1979, the Soviet Union launched the four-satellite “Cicada” constellation, and by 1993, the GLONASS system had been formally declared operational. It now has a nominal constellation of 24 satellites, just like the GPS. However, there are significant variations to be aware of. For starters, the GLONASS ephemeris update would happen more frequently, every half hour.
BeiDou
No, this is not based on a character from Genshin Impact!
Yet they might still share certain traits. The Ursa Major’s seven prominent stars, known in Chinese as the Big Dipper or Plough, inspired the name of the BeiDou Navigation Satellite System (BDS). To establish a system “suited for its national conditions,” the People’s Republic of China developed BeiDou in the late 20th century.
The initial BeiDou constellation, consisting of three satellites, was finished in 2000–2003. Since then, the system has expanded and managed 35 satellites for its space section. The Chinese government, which asserts that BeiDou is on par with GPS, has been heralding the rapid advancement of technology worldwide.
Galileo
Galileo was purported to have been developed by the European Union primarily for civilian purposes, maybe in contrast to the previous three systems, which were purported to have had military applications in their various historical phases. By 2021, the Galileo space segment will have a constellation with at least 24 satellites. Galileo would operate at altitudes higher than those typically used by GPS, GLONASS, and BeiDou to improve positioning accuracy for civilian users. Galileo’s ephemeris would be updated every three hours, though.
How they operate?
Due to the law of inertia, satellites are predicted to circle the Earth continuously when in orbit. In other words, the delicate balance between the satellite’s velocity and gravitational pull prevents them from “bouncing off” into the vastness of space or being consumed by the Earth’s atmosphere. It would follow a similar theory regarding how the Earth and the Moon interact. Trilateration is the process these satellites employ to determine your exact location. As each satellite attempts to calculate your distance from them, signals are emitted within their respective circles, and the number of satellites increases the accuracy of the calculation.
The satellites’ internal clocks can track your whereabouts in real time. Our electronics, including phones, automobiles, and even fitness trackers, maybe the receivers of these signals. Although accuracy may vary for several reasons, including local weather conditions, certain receivers are believed to be able to pinpoint a location within one centimeter. At this point, it becomes clear how important it is to have many systems in your receivers because it gives you the chance to get even more accurate mapping results.
Regional constellations would exist in addition to the systems, as mentioned earlier, covering more specialized regions of the Earth. Of course, another conversation might be better suited to this topic.
