Let’s define the term “artificial satellite”. An artificial satellite refers to a man-made object orbiting the Earth or another celestial body. The purpose of artificial satellites is to collect information about Earth or other celestial bodies, perform tasks such as communication, exploration, and Earth observation. These objects are launched into space from the Earth’s surface via rockets and orbit specific paths outside the Earth’s atmosphere to carry out their missions. In summary, artificial satellites are artificially created celestial bodies with specific purpose, orbiting specific paths.
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What is an artificial satellite.
When we think of artificial satellites, images of weather satellites capturing the eye of a storm, communication satellites, and GPS satellites providing our current location may come to mind. But what exactly are artificial satellites, what types exist, and what’s inside them?
Orbit Classification
In essence, artificial satellites are man-made objects orbiting several hundred to several thousand kilometers above the Earth’s surface, engaging in communication with Earth and other data-related tasks. Let’s delve into orbits. There are primarily three types: LEO, MEO, and GEO.
Let’s start with LEO, or Low Earth Orbit. LEO refers to orbits relatively close to Earth’s atmosphere, typically below 2,000km in altitude. They’re mainly used for Earth observation, communication, weather forecasting, etc. LEO’s advantages include low orbit altitude, resulting in short latency and minimal atmospheric resistance, leading to low fuel consumption. However, due to their low orbits, they cover small radii and require multiple satellites for continuous communication.
Next is MEO, or Medium Earth Orbit, positioned between LEO and GEO, roughly between 2,000km to 35,786km in altitude. They’re commonly utilized for systems like GPS. MEO offers wider coverage and continuous communication capabilities compared to LEO, but they entail slightly higher latency and require more fuel for orbit maintenance than GEO.
Lastly, there’s GEO, or Geostationary Earth Orbit, located at approximately 35,786km altitude, synchronized with Earth’s rotation, maintaining a fixed position relative to the surface. GEO satellites are ideal for communication, broadcasting, and weather monitoring due to their stationary position and wide coverage. However, they suffer from higher latency, increased fuel consumption to stay in orbit, and require precise control.
In summary, artificial satellites come in different orbits, each serving specific purposes with distinct advantages and limitations. Understanding these orbit types is crucial for designing, launching, and operating satellites effectively.
Composition of an artificial satellite system
The composition of an artificial satellite system can be broadly divided into two main components: the Spacecraft and the Ground Station. Within the Spacecraft component, there are two further subdivisions: the Bus and the Payload.
Spacecraft (S/C): The spacecraft is the core of an artificial satellite and is composed of various components. This includes the external structure and internal systems of the satellite. The external structure encompasses the satellite’s chassis, thermal protection, solar panels, antennas, and more. Meanwhile, internal systems include power supply, communication equipment, solar panel arrays, sensors, control systems, and others.
Bus: The bus serves as the fundamental platform responsible for the basic operation of the satellite. This includes power management, attitude control, communication, data processing, and more. The bus is primarily composed of the satellite’s structure, power systems, attitude control systems, communication systems, computers, and related components.
Payload: The payload consists of equipment that performs the satellite’s primary mission. For instance, in a communication satellite, the payload includes communication equipment, while in an observation satellite, it comprises cameras or sensors. The payload mainly consists of hardware and software related to the satellite’s primary mission.
Ground Station: The ground station manages communication between the satellite and the ground, as well as collects data. It is responsible for executing commands to the satellite, receiving and processing data down-linked from the satellite. Ground stations include software and hardware necessary for tasks such as coordinate transformations between ground and satellite coordinates and data processing.