Artificial satellites are man-made objects that revolve around the Earth and other planets in the solar system. It differs from natural satellites or moons, and from orbiting planets, dwarf planets, and even asteroids. Artificial satellites are used to study the Earth, other planets, help us communicate, and even observe the distant universe. Humans can also exist in satellites, such as the International Space Station and the space shuttle.
The first artificial satellite was the Soviet Sputnik 1 mission, launched in 1957. Since then, dozens of countries have launched satellites, with more than 3,000 currently circling around the Earth. The space is estimated to contain over 8,000 pieces of waste; Dead satellites or pieces of debris are floating around the Earth.
The satellites are launched in various orbits depending on their mission. One of the most common is the geosynchronous class. This is where a satellite takes 24 hours to orbit the Earth; It takes the same amount of time for the Earth to rotate once on its axis. This puts the satellite in one place on Earth, which helps in communication and television broadcasting.
Another orbit is a low-Earth orbit, where a satellite can be only a few hundred kilometers above the planet. This puts the satellite outside the Earth’s atmosphere, but is still so close that it can see the planet’s surface from space or facilitate communication. This is the height at which the spacecraft flies, as well as the Hubble Space Telescope.
Artificial satellites can have multiple missions, including scientific research, weather observation, logistical support, navigation, earth imaging and communications. Some satellites serve the same purpose, while others are designed to perform multiple tasks at the same time. On a satellite, the device is hardened to survive the radiation and vacuum of space.
The satellites are manufactured by various aerospace companies, such as Boeing or Lockheed, and then delivered to a launch facility such as Cape Canaveral. Launch facilities can be as close to the Earth’s equator as possible to give an extra speed to space. This allows rockets to use less fuel or launch heavier payloads.
The height of the satellite’s orbit defines how long it will stay in orbit. Low-orbiting satellites are mostly above the Earth’s atmosphere, but they are still affected by the atmosphere and their orbit eventually deteriorates and falls back into the atmosphere. Other satellites orbiting in high orbits will likely last for millions of years.