How do Satellites Work?

Satellites are an indispensable part of our daily lives, from enabling global communication to forecasting weather. Their story begins in the thick of the Cold War, with the space race acting as a catalyst for rapid technological advancements. It was during this period of intense competition between the United States and the Soviet Union that the first artificial satellite, Sputnik, was launched in 1957. This groundbreaking event not only marked the start of space exploration but also demonstrated the potential of satellites. Not long after, the United States launched its first satellite, Explorer 1, in 1958. In 1962, the UK proudly sent its first satellite, Ariel 1, into space, only for it to become damaged by a US space nuclear weapons test three months later.
The journey of a satellite begins with a rocket launch. Once in space, it enters an orbit - a carefully calculated path that ensures the satellite remains in motion around the Earth.
Satellites orbit Earth in different ways based on their mission. Low Earth Orbit (LEO) is close to Earth and suitable for detailed imaging and science missions. Medium Earth Orbit (MEO) is higher and is commonly used for GPS navigation systems. Geostationary Orbit (GEO) remains in a fixed position relative to Earth’s spin, ideal for communication and weather monitoring. Sun-synchronous orbits, a type of LEO, maintain a consistent position relative to the Sun, ensuring the satellite passes over the same area at the same local solar time each orbit, which is helpful for consistent lighting in images. Highly Elliptical Orbits (HEO) provide extended coverage over specific areas.
Sometimes, satellites are positioned at Lagrange Points. These points are stable points in space where the gravitational forces of Earth and another body, like the Sun, exert the same force on the satellite, keeping it stationary relative to the two bodies. Lagrange Point satellites are advantageous for long-term observation; for example, those positioned between the Earth and the Sun allow us to forecast potential hazards such as intense solar storms.
Most modern satellites use solar panels to harness energy from the Sun, which is then stored in batteries. A minority of satellites have relied on nuclear power. However, the practice has become increasingly rare.
Satellite communication encompasses a diverse array of methods, including not just sophisticated ground stations and transmitters but also accessible options like regular TV antennas. This variety in technology facilitates a wide range of transmissions, from GPS navigation on your phone to live international broadcasts. Interestingly, even DIY enthusiasts can communicate with satellites, as demonstrated in projects like TheThoughtEmporium’s video, where he directly pulls images from orbiting satellites.
Speaking of GPS, the Global Positioning System (GPS) operates via a constellation of over 30 satellites in Medium Earth Orbit. These satellites continuously emit signals. GPS receivers, like the ones in smartphones, determine their exact position by calculating how far away they are from at least four satellites. This calculation is done using trilateration. Trilateration finds a place by measuring its distance from three or more known spots. Think of three circles, each with a center at these known spots - the circles are as big as the distance to the unknown place. The unknown place, or the position of the GPS user, is precisely where the three circles meet. GPS is highly accurate, typically locating objects within a few centimeters.
Innovation in satellite technology is advancing rapidly. Newer satellites are smaller, cheaper, and more efficient, opening up possibilities for more extensive and diverse applications. We’re also witnessing the emergence of mega-constellations - networks of hundreds or even thousands of satellites working together to provide global internet coverage or comprehensive Earth observations - like SpaceX’s Starlink.
The flip side of this technological marvel is a dramatic increase in the volume of satellites cluttering Earth’s orbit.
Sources:
1. "How Satellites Work” - HowStuffWorks
2. "Space Debris: Tackling the Problem” - Space Data Association
3. “How Does GPS Work?” - NASA
4. “Catalog of Earth Satellite Orbits” - NASA
5. “Types of Orbits” - Space Foundation
6. “The History of Nuclear Power in Space” - Department of Energy, USA
7. How to Pull Images from Satellites in Orbit (NOAA 15,18,19 and METEOR M2) - TheThoughtEmporoim, CZcams
8. An Early History of Satellites Timeline - NASA Jet Propulsion Laboratory
Editing by Myles Adoh-Phillips
Written by Lucas L

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